A major endeavor of this decade is the direct characterization of young giant exoplanets at high spectral resolution to determine the composition of
their atmosphere and infer their formation processes and evolution. Such a goal represents a major challenge owing to their small angular separation
and luminosity contrast with respect to their parent stars. Instead of designing and implementing completely new facilities, it has been proposed
to leverage the capabilities of existing instruments that offer either high contrast imaging or high dispersion spectroscopy, by coupling them using
optical fibers. In this work we present the implementation and first on-sky results of the HiRISE instrument at the very large telescope (VLT),
which combines the exoplanet imager SPHERE with the recently upgraded high resolution spectrograph CRIRES using single-mode fibers. The
goal of HiRISE is to enable the characterization of known companions in the H band, at a spectral resolution of the order of R = λ/∆λ = 100 000,
in a few hours of observing time. We present the main design choices and the technical implementation of the system, which is constituted of three
major parts: the fiber injection module inside of SPHERE, the fiber bundle around the telescope, and the fiber extraction module at the entrance
of CRIRES. We also detail the specific calibrations required for HiRISE and the operations of the instrument for science observations. Finally, we
detail the performance of the system in terms of astrometry, temporal stability, optical aberrations, and transmission, for which we report a peak
value of ∼3.9% based on sky measurements in median observing conditions. Finally, we report on the first astrophysical detection of HiRISE to
illustrate its potential.
The Second Data Release of the INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS) provides single-epoch photometry for 219 million unique sources across 92% of the survey's footprint. The survey used the Wide Field Camera on the Isaac Newton Telescope to image a region of the northern Galactic plane in Sloan r, i, and narrowband Hα filters between 2003-2012. The data were reduced and calibrated using procedures developed for the INT Wide Field Survey. A global re-calibration was performed using the AAVSO Photometric All-Sky Survey and the Sloan Digital Sky Survey, achieving an accuracy of 0.03 mag. The catalogue characterizes stellar populations and extinction across different Galactic sightlines and
High-resolution UV/Optical/IR Imaging of Jupiter in 2016–2019Sérgio Sacani
Imaging observations of Jupiter with high spatial resolution were acquired beginning in 2016, with a cadence of 53
days to coincide with atmospheric observations of the Juno spacecraft during each perijove pass. The Wide Field
Camera 3 (WFC3) aboard the Hubble Space Telescope (HST) collected Jupiter images from 236 to 925 nm in 14
filters. The Near-Infrared Imager (NIRI) at Gemini North imaged Jovian thermal emission using a lucky-imaging
approach (co-adding the sharpest frames taken from a sequence of short exposures), using the M′ filter at 4.7 μm.
We discuss the data acquisition and processing and an archive collection that contains the processed WFC3 and
NIRI data (doi:10.17909/T94T1H). Zonal winds remain steady over time at most latitudes, but significant
evolution of the wind profile near 24°N in 2016 and near 15°S in 2017 was linked with convective superstorm
eruptions. Persistent mesoscale waves were seen throughout the 2016–2019 period. We link groups of lightning
flashes observed by the Juno team with water clouds in a large convective plume near 15°S and in cyclones near
35°N–55°N. Thermal infrared maps at the 10.8 micron wavelength obtained at the Very Large Telescope show
consistent high brightness temperature anomalies, despite a diversity of aerosol properties seen in the HST data.
Both WFC3 and NIRI imaging reveal depleted aerosols consistent with downwelling around the periphery of the
15°S storm, which was also observed by the Atacama Large Millimeter/submillimeter Array. NIRI imaging of
the Great Red Spot shows that locally reduced cloud opacity is responsible for dark features within the vortex. The
HST data maps multiple concentric polar hoods of high-latitude hazes.
Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 bSérgio Sacani
Context. WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy
data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by
multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the
infrared (IR) phase curve.
Aims. We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes
at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband
phase curves.
Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope.
We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents
34 phase curves.
Results. WASP-76 b displays an occultation of 260±11 and 152±10 ppm in TESS and CHEOPS bandpasses respectively. Depending
on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates
that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As
expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either.
However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an
amplitude of ∼40 ppm, an orbital offset of ∼−30◦
, and a width of ∼20◦
. We also constrained the orbital eccentricity of WASP-76 b to
a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the
asymmetry observed in high-resolution transit spectroscopy.
Conclusions. In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly
towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an
unknown species, which would be responsible for a glory effect in the visible phase curves.
Beyond the disk: EUV coronagraphic observations of the Extreme Ultraviolet Im...Sérgio Sacani
Most observations of the solar corona beyond 2 R consist of broadband visible light imagery carried out with coronagraphs.
The associated diagnostics mainly consist of kinematics and derivations of the electron number density. While the measurement of the
properties of emission lines can provide crucial additional diagnostics of the coronal plasma (temperatures, velocities, abundances,
etc.), these types of observations are comparatively rare. In visible wavelengths, observations at these heights are limited to total
eclipses. In the ultraviolet (UV) to extreme UV (EUV) range, very few additional observations have been achieved since the pioneering
results of the Ultraviolet Coronagraph Spectrometer (UVCS).
Aims. One of the objectives of the Full Sun Imager (FSI) channel of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter
mission has been to provide very wide field-of-view EUV diagnostics of the morphology and dynamics of the solar atmosphere in
temperature regimes that are typical of the lower transition region and of the corona.
Methods. FSI carries out observations in two narrowbands of the EUV spectrum centered on 17.4 nm and 30.4 nm that are dominated,
respectively, by lines of Fe ix/x (formed in the corona around 1 MK) and by the resonance line of He ii (formed around 80 kK in the
lower transition region). Unlike previous EUV imagers, FSI includes a moveable occulting disk that can be inserted in the optical path
to reduce the amount of instrumental stray light to a minimum.
Results. FSI detects signals at 17.4 nm up to the edge of its field of view (7 R), which is about twice further than was previously
possible. Operation at 30.4 nm are for the moment compromised by an as-yet unidentified source of stray light. Comparisons with
observations by the LASCO and Metis coronagraphs confirm the presence of morphological similarities and differences between the
broadband visible light and EUV emissions, as documented on the basis of prior eclipse and space-based observations.
Conclusions. The very-wide-field observations of FSI out to about 3 and 7 R, without and with the occulting disk, respectively, are
paving the way for future dedicated instruments.
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
This document describes a public release of photometric redshifts and galaxy properties from multi-wavelength data in the Abell-2744 and MACS-J0416 galaxy cluster fields observed as part of the Frontier Fields program. Photometric redshifts were estimated using six different methods and have an accuracy of 3-5%. Accounting for gravitational lensing magnification, the H-band number counts agree with CANDELS at bright magnitudes but extend to intrinsically fainter galaxies of H=32-33. The Frontier Fields data allow probing galaxy stellar masses 0.5-1.5 dex lower than in wide fields, including sources with masses of 107-108 solar masses at z>5. Star formation rates can be detected 1
The herschel view_of_massive_star_formation_in_dense_and_cold_filament_w48Sérgio Sacani
The Herschel Space Observatory observed the IRDC filament G035.39–00.33 in the W48 molecular cloud complex. The observations revealed 28 compact dense cores, 13 of which have masses greater than 20 solar masses. These massive dense cores are excellent candidates to form intermediate- to high-mass stars. Most of the massive dense cores are located within the G035.39–00.33 filament and contain infrared-quiet high-mass protostars. The large number of protostars suggests a "mini-burst" of star formation is occurring within the filament, with an efficiency of about 15% and a formation rate of around 40 solar masses per year per square kiloparsec. Some extended Si
The muse 3_d_view_of_the_hubble_deep_field_southSérgio Sacani
Artigo mostra como foram as observações feitas com o MUSE, o novo instrumento do VLT do campo profundo do Hubble. Além de descobrir 20 novos objetos, o MUSE conseguiu medir as propriedades das galáxias e até representar as mais próximas em 3 dimensões.
Detection of an atmosphere around the super earth 55 cancri eSérgio Sacani
We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near
infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent
star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness
of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length
and a very high scanning speed. We use our specialized pipeline to take into account systematics
introduced by these observational parameters when coupled with the geometrical distortions of the
instrument. We measure the transit depth per wavelength channel with an average relative uncertainty
of 22 ppm per visit and nd modulations that depart from a straight line model with a 6 condence
level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably
hydrogen-rich. Our fully Bayesian spectral retrieval code, T -REx, has identied HCN to be the
most likely molecular candidate able to explain the features at 1.42 and 1.54 m. While additional
spectroscopic observations in a broader wavelength range in the infrared will be needed to conrm
the HCN detection, we discuss here the implications of such result. Our chemical model, developed
with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a
high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic
than previously thought.
The Second Data Release of the INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS) provides single-epoch photometry for 219 million unique sources across 92% of the survey's footprint. The survey used the Wide Field Camera on the Isaac Newton Telescope to image a region of the northern Galactic plane in Sloan r, i, and narrowband Hα filters between 2003-2012. The data were reduced and calibrated using procedures developed for the INT Wide Field Survey. A global re-calibration was performed using the AAVSO Photometric All-Sky Survey and the Sloan Digital Sky Survey, achieving an accuracy of 0.03 mag. The catalogue characterizes stellar populations and extinction across different Galactic sightlines and
High-resolution UV/Optical/IR Imaging of Jupiter in 2016–2019Sérgio Sacani
Imaging observations of Jupiter with high spatial resolution were acquired beginning in 2016, with a cadence of 53
days to coincide with atmospheric observations of the Juno spacecraft during each perijove pass. The Wide Field
Camera 3 (WFC3) aboard the Hubble Space Telescope (HST) collected Jupiter images from 236 to 925 nm in 14
filters. The Near-Infrared Imager (NIRI) at Gemini North imaged Jovian thermal emission using a lucky-imaging
approach (co-adding the sharpest frames taken from a sequence of short exposures), using the M′ filter at 4.7 μm.
We discuss the data acquisition and processing and an archive collection that contains the processed WFC3 and
NIRI data (doi:10.17909/T94T1H). Zonal winds remain steady over time at most latitudes, but significant
evolution of the wind profile near 24°N in 2016 and near 15°S in 2017 was linked with convective superstorm
eruptions. Persistent mesoscale waves were seen throughout the 2016–2019 period. We link groups of lightning
flashes observed by the Juno team with water clouds in a large convective plume near 15°S and in cyclones near
35°N–55°N. Thermal infrared maps at the 10.8 micron wavelength obtained at the Very Large Telescope show
consistent high brightness temperature anomalies, despite a diversity of aerosol properties seen in the HST data.
Both WFC3 and NIRI imaging reveal depleted aerosols consistent with downwelling around the periphery of the
15°S storm, which was also observed by the Atacama Large Millimeter/submillimeter Array. NIRI imaging of
the Great Red Spot shows that locally reduced cloud opacity is responsible for dark features within the vortex. The
HST data maps multiple concentric polar hoods of high-latitude hazes.
Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 bSérgio Sacani
Context. WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy
data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by
multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the
infrared (IR) phase curve.
Aims. We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes
at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband
phase curves.
Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope.
We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents
34 phase curves.
Results. WASP-76 b displays an occultation of 260±11 and 152±10 ppm in TESS and CHEOPS bandpasses respectively. Depending
on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates
that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As
expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either.
However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an
amplitude of ∼40 ppm, an orbital offset of ∼−30◦
, and a width of ∼20◦
. We also constrained the orbital eccentricity of WASP-76 b to
a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the
asymmetry observed in high-resolution transit spectroscopy.
Conclusions. In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly
towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an
unknown species, which would be responsible for a glory effect in the visible phase curves.
Beyond the disk: EUV coronagraphic observations of the Extreme Ultraviolet Im...Sérgio Sacani
Most observations of the solar corona beyond 2 R consist of broadband visible light imagery carried out with coronagraphs.
The associated diagnostics mainly consist of kinematics and derivations of the electron number density. While the measurement of the
properties of emission lines can provide crucial additional diagnostics of the coronal plasma (temperatures, velocities, abundances,
etc.), these types of observations are comparatively rare. In visible wavelengths, observations at these heights are limited to total
eclipses. In the ultraviolet (UV) to extreme UV (EUV) range, very few additional observations have been achieved since the pioneering
results of the Ultraviolet Coronagraph Spectrometer (UVCS).
Aims. One of the objectives of the Full Sun Imager (FSI) channel of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter
mission has been to provide very wide field-of-view EUV diagnostics of the morphology and dynamics of the solar atmosphere in
temperature regimes that are typical of the lower transition region and of the corona.
Methods. FSI carries out observations in two narrowbands of the EUV spectrum centered on 17.4 nm and 30.4 nm that are dominated,
respectively, by lines of Fe ix/x (formed in the corona around 1 MK) and by the resonance line of He ii (formed around 80 kK in the
lower transition region). Unlike previous EUV imagers, FSI includes a moveable occulting disk that can be inserted in the optical path
to reduce the amount of instrumental stray light to a minimum.
Results. FSI detects signals at 17.4 nm up to the edge of its field of view (7 R), which is about twice further than was previously
possible. Operation at 30.4 nm are for the moment compromised by an as-yet unidentified source of stray light. Comparisons with
observations by the LASCO and Metis coronagraphs confirm the presence of morphological similarities and differences between the
broadband visible light and EUV emissions, as documented on the basis of prior eclipse and space-based observations.
Conclusions. The very-wide-field observations of FSI out to about 3 and 7 R, without and with the occulting disk, respectively, are
paving the way for future dedicated instruments.
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
This document describes a public release of photometric redshifts and galaxy properties from multi-wavelength data in the Abell-2744 and MACS-J0416 galaxy cluster fields observed as part of the Frontier Fields program. Photometric redshifts were estimated using six different methods and have an accuracy of 3-5%. Accounting for gravitational lensing magnification, the H-band number counts agree with CANDELS at bright magnitudes but extend to intrinsically fainter galaxies of H=32-33. The Frontier Fields data allow probing galaxy stellar masses 0.5-1.5 dex lower than in wide fields, including sources with masses of 107-108 solar masses at z>5. Star formation rates can be detected 1
The herschel view_of_massive_star_formation_in_dense_and_cold_filament_w48Sérgio Sacani
The Herschel Space Observatory observed the IRDC filament G035.39–00.33 in the W48 molecular cloud complex. The observations revealed 28 compact dense cores, 13 of which have masses greater than 20 solar masses. These massive dense cores are excellent candidates to form intermediate- to high-mass stars. Most of the massive dense cores are located within the G035.39–00.33 filament and contain infrared-quiet high-mass protostars. The large number of protostars suggests a "mini-burst" of star formation is occurring within the filament, with an efficiency of about 15% and a formation rate of around 40 solar masses per year per square kiloparsec. Some extended Si
The muse 3_d_view_of_the_hubble_deep_field_southSérgio Sacani
Artigo mostra como foram as observações feitas com o MUSE, o novo instrumento do VLT do campo profundo do Hubble. Além de descobrir 20 novos objetos, o MUSE conseguiu medir as propriedades das galáxias e até representar as mais próximas em 3 dimensões.
Detection of an atmosphere around the super earth 55 cancri eSérgio Sacani
We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near
infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent
star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness
of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length
and a very high scanning speed. We use our specialized pipeline to take into account systematics
introduced by these observational parameters when coupled with the geometrical distortions of the
instrument. We measure the transit depth per wavelength channel with an average relative uncertainty
of 22 ppm per visit and nd modulations that depart from a straight line model with a 6 condence
level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably
hydrogen-rich. Our fully Bayesian spectral retrieval code, T -REx, has identied HCN to be the
most likely molecular candidate able to explain the features at 1.42 and 1.54 m. While additional
spectroscopic observations in a broader wavelength range in the infrared will be needed to conrm
the HCN detection, we discuss here the implications of such result. Our chemical model, developed
with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a
high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic
than previously thought.
Imaging the Milky Way with Millihertz Gravitational WavesSérgio Sacani
Modern astronomers enjoy access to all-sky images across a wide range of the electromagnetic spectrum from
long-wavelength radio to high-energy gamma rays. The most prominent feature in many of these images is our
own Galaxy, with different features revealed in each wave band. Gravitational waves (GWs) have recently been
added to the astronomers’ toolkit as a nonelectromagnetic messenger. To date, all identified GW sources have been
extra-Galactic and transient. However, the Milky Way hosts a population of ultracompact binaries (UCBs), which
radiate persistent GWs in the milliHertz band that is not observable with today’s terrestrial gravitational-wave
detectors. Space-based detectors such as the Laser Interferometer Space Antenna will measure this population and
provide a census of their location, masses, and orbital properties. In this work, we will show how this data can be
used to form a false-color image of the Galaxy that represents the intensity and frequency of the gravitational
waves produced by the UCB population. Such images can be used to study the morphology of the Galaxy, identify
interesting multimessenger sources through cross-matching, and for educational and outreach purposes.
A Simultaneous dual-site technosignature search using international LOFAR sta...Sérgio Sacani
The Search for Extraterrestrial Intelligence (SETI) aims to find evidence of technosignatures, which
can point towards the possible existence of technologically advanced extraterrestrial life. Radio signals
similar to those engineered on Earth may be transmitted by other civilizations, motivating technosignature searches across the entire radio spectrum. In this endeavor, the low-frequency radio band
has remained largely unexplored; with prior radio searches primarily above 1 GHz. In this survey at
110 − 190 MHz, observations of 1,631,198 targets from TESS and Gaia are reported. Observations
took place simultaneously with two international stations (non-interferometric) of the Low Frequency
Array in Ireland and Sweden. We can reject the presence of any Doppler drifting narrow-band transmissions in the barycentric frame of reference, with equivalent isotropic radiated power of 1017 W, for
0.4 million (or 1.3 million) stellar systems at 110 (or 190) MHz. This work demonstrates the effectiveness of using multi-site simultaneous observations for rejecting anthropogenic signals in the search for
technosignatures.
This document summarizes a blind HI survey of the southern Milky Way zone of avoidance conducted with the Parkes radio telescope. The survey detected 883 galaxies at Galactic longitudes 212° < l < 36° and latitudes |b| < 5° to a sensitivity of 6 mJy per 27 km/s channel. Fifty-one percent of detections had known optical/near-infrared counterparts, while 27% had new counterparts identified. The survey delineated large-scale structures in the Puppis and Great Attractor regions for the first time. Several newly identified galaxy concentrations and clusters were revealed that help trace the Great Attractor Wall.
Mapping the Skies of Ultracool Worlds: Detecting Storms and Spots with Extrem...Sérgio Sacani
Extremely large telescopes (ELTs) present an unparalleled opportunity to study the magnetism,
atmospheric dynamics, and chemistry of very low mass stars (VLMs), brown dwarfs, and exoplanets.
Instruments such as the Giant Magellan Telescope - Consortium Large Earth Finder (GMT/GCLEF),
the Thirty Meter Telescope’s Multi-Objective Diffraction-limited High-Resolution Infrared Spectrograph
(TMT/MODHIS), and the European Southern Observatory’s Mid-Infrared ELT Imager and Spectrograph (ELT/METIS) provide the spectral resolution and signal-to-noise (S/N) necessary to Doppler
image ultracool targets’surfaces based on temporal spectral variations due to surface inhomogeneities.
Using our publicly-available code, Imber, developed and validated in Plummer & Wang (2022), we
evaluate these instruments’abilities to discern magnetic star spots and cloud systems on a VLM star
(TRAPPIST-1); two L/T transition ultracool dwarfs (VHS J1256−1257 b and SIMP J0136+0933); and
three exoplanets (Beta Pic b and HR 8799 d and e). We find that TMT/MODHIS and ELT/METIS are
suitable for Doppler imaging the ultracool dwarfs and Beta Pic b over a single rotation. Uncertainties
for longitude and radius are typically . 10◦
, and latitude uncertainties range from ∼ 10◦
to 30◦
.
TRAPPIST-1’s edge-on inclination and low υ sin i provide a challenge for all three instruments while
GMT/GCLEF and the HR 8799 planets may require observations over multiple rotations. We compare
the spectroscopic technique, photometry-only inference, and the combination of the two. We find
combining spectroscopic and photometric observations can lead to improved Bayesian inference of
surface inhomogeneities and offers insight into whether ultracool atmospheres are dominated by spotted
or banded features.
First wide field-of-view X-ray observations by a lobster eye focusing telesco...Sérgio Sacani
The document describes the first results from LEIA, a lobster eye X-ray telescope launched as a pathfinder for the Einstein Probe mission. Key results include:
- LEIA has a wide field of view of 18.6°x18.6° and achieved its expected spatial resolution of 4-7 arcmin and effective area of 2-3 cm^2 across most of the field of view.
- LEIA took snapshot images of the Galactic center region, Sco X-1, and the Cygnus Loop nebula, representing the first truly wide-field X-ray images captured by a focusing X-ray telescope.
- Initial analyses found excellent agreement between the observed images and ground cal
Orbital configurations of spaceborne interferometers for studying photon ring...Sérgio Sacani
Recent advances in technology coupled with the progress of observational
radio astronomy methods resulted in achieving a major milestone of astrophysics - a direct image of the shadow of a supermassive black hole, taken
by the Earth-based Event Horizon Telescope (EHT). The EHT was able to
achieve a resolution of ∼20 µas, enabling it to resolve the shadows of the
black holes in the centres of two celestial objects: the supergiant elliptical
galaxy M87 and the Milky Way Galaxy. The EHT results mark the start of a
new round of development of next generation Very Long Baseline Interferometers (VLBI) which will be able to operate at millimetre and sub-millimetre
wavelengths. The inclusion of baselines exceeding the diameter of the Earth
and observation at as short a wavelength as possible is imperative for further development of high resolution astronomical observations. This can be
achieved by a spaceborne VLBI system. We consider the preliminary mission
design of such a system, specifically focused on the detection and analysis
of photon rings, an intrinsic feature of supermassive black holes. Optimised
Earth, Sun-Earth L2 and Earth-Moon L2 orbit configurations for the space
interferometer system are presented, all of which provide an order of magnitude improvement in resolution compared to the EHT. Such a space-borne
A Search for Technosignatures Around 11,680 Stars with the Green Bank Telesco...Sérgio Sacani
We conducted a search for narrowband radio signals over four observing sessions in 2020–2023 with
the L-band receiver (1.15–1.73 GHz) of the 100 m diameter Green Bank Telescope. We pointed the
telescope in the directions of 62 TESS Objects of Interest, capturing radio emissions from a total of
∼11,860 stars and planetary systems in the ∼9 arcminute beam of the telescope. All detections were
either automatically rejected or visually inspected and confirmed to be of anthropogenic nature. In
this work, we also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection
and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable
frequency range of the receiver and 98.7% of the injections when regions of dense RFI are excluded. In
another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ∼15 times
smaller at ∼6%. The pipeline efficiency affects SETI search volume calculations as well as calculations
of upper bounds on the number of transmitting civilizations. We developed an improved Drake Figure
of Merit for SETI search volume calculations that includes the pipeline efficiency and frequency drift
rate coverage. Based on our observations, we found that there is a high probability (94.0–98.7%) that
fewer than ∼0.014% of stars earlier than M8 within 100 pc host a transmitter that is detectable in
our search (EIRP > 1012 W). Finally, we showed that the UCLA SETI pipeline natively detects the
signals detected with AI techniques by Ma et al. (2023).
This document summarizes observations of the lensed galaxy HATLAS J142935.3-002836 (H1429-0028) from the Herschel-ATLAS survey. Optical spectroscopy revealed the foreground lens is at redshift 0.218, while the background galaxy is at redshift 1.027. High-resolution imaging from Hubble Space Telescope and Keck adaptive optics show the background galaxy is comprised of two components and a tidal tail, resembling a major merger. Analysis of ALMA observations of CO emission provides a dynamical mass estimate of one component as 5.8 ± 1.7 × 1010 M☉. Modeling of the spectral energy distribution indicates the total stellar mass is 1.32
First Direct Imaging of a Kelvin–Helmholtz Instability by PSP/WISPRSérgio Sacani
We present a comprehensive analysis aimed at proving the hypothesis that a train of small-scale features observed by the Wide-field Imager (WISPR) onboard the Parker Solar Probe (PSP) are the signature of a Kelvin–Helmholtz instability (KHI). These features were seen near the flank of a Coronal Mass Ejection (CME) wake between 7.5 Re and 9.5Re, lasting for about 30 minutes. The CME was a slow event, associated with a streamer blowout. We analyzed the size of the eddies and found growth during their evolution while maintaining separation distances and alignment typical of Kelvin–Helmholtz vortexes. We then assessed the magnetic field conditions that would make the observation of such an instability plausible. Two methods were used to cross-check our findings. The measured thickness of the boundary layer supports KHI candidacy, and the estimated linear growth rate suggests nonlinear saturation within the expected timescale. We conclude that a KHI is a plausible explanation for the observed features, and therefore that such instabilities might exist in the low and middle solar corona (within ∼15 Re) and can be detected in white light observations. Their observation, however, might be rare due to stringent conditions like the observer’s proximity, suitable viewing circumstances, magnetic field topology, and flow properties. This study highlights the unique capability of PSP/WISPR in observing such phenomena, especially as PSP perihelia reach closer distances to the Sun.
The Large Interferometer For Exoplanets (LIFE) II: Key Methods and TechnologiesAdvanced-Concepts-Team
The LIFE initiative has the goal to develop the science, the technology and a roadmap for an aspiring space mission that will allow humankind to detect and characterize, via nulling interferometry, the atmospheres of hundreds of nearby extrasolar planets including dozens that may be similar to Earth. This follow-up talk will tackle more of the techniques and technologies that will enable such an ambitious undertaking. I will outline the underlying measuring principle, and provide some overview over essential technologies, their current status and necessary developments.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
GOALS-JWST: Unveiling Dusty Compact Sources in the Merging Galaxy IIZw096Sérgio Sacani
We have used the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) to obtain the first
spatially resolved, mid-infrared images of IIZw096, a merging luminous infrared galaxy (LIRG) at z = 0.036.
Previous observations with the Spitzer Space Telescope suggested that the vast majority of the total IR luminosity
(LIR) of the system originated from a small region outside of the two merging nuclei. New observations with
JWST/MIRI now allow an accurate measurement of the location and luminosity density of the source that is
responsible for the bulk of the IR emission. We estimate that 40%–70% of the IR bolometric luminosity, or
3–5 × 1011 Le, arises from a source no larger than 175 pc in radius, suggesting a luminosity density of at least
3–5 × 1012 Le kpc−2
. In addition, we detect 11 other star-forming sources, five of which were previously
unknown. The MIRI F1500W/F560W colors of most of these sources, including the source responsible for the
bulk of the far-IR emission, are much redder than the nuclei of local LIRGs. These observations reveal the power
of JWST to disentangle the complex regions at the hearts of merging, dusty galaxies.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
VISIONS: The VISTA Star Formation AtlasSérgio Sacani
The VISIONS survey observed five nearby star-forming regions in the near-infrared using the VISTA telescope over a period of 5 years. It collected 1.15 million images totaling 19 TB of raw data. The survey was designed to build an infrared legacy archive similar to 2MASS but probing embedded objects. It used three subsurveys - a wide subsurvey with shallow observations covering large areas, a deep subsurvey targeting regions of high dust extinction, and a control subsurvey of low extinction areas. The goal was to characterize young stellar objects, study stellar and cluster formation and evolution, and measure proper motions to complement the Gaia mission.
Confirmation of the_ogle_planet_signature_and_its_characteristics_with_lens_s...Sérgio Sacani
O Telescópio Espacial Hubble e o Observatório W. M. Keck, no Havaí, fizeram confirmações independentes de um exoplaneta orbitando sua estrela central de uma distância bem grande. O planeta foi descoberto através de uma técnica chamada de microlente gravitacional.
Essa descoberta traz uma nova peça para o processo de caçada de exoplanetas: para descobrir planetas longe de suas estrelas, como Júpiter e Saturno estão do Sol. Os resultados obtidos pelo Hubble e pelo Keck apareceram em dois artigos da edição de 30 de Julho de 2015 do The Astrophysical Journal.
A grande maioria dos exoplanetas catalogados são aqueles localizados bem perto de suas estrelas, isso acontece porque as técnicas atuais de se caçar exoplanetas favorecem a descoberta de planetas com curtos períodos orbitais. Mas esse não é o caso da técnica de microlente gravitacional, que pode encontrar planetas mais frios e mais distantes com órbitas de longo período que outros métodos não são capazes de detectar.
AT2023fhn (the Finch): a Luminous Fast Blue Optical Transient at a large offs...Sérgio Sacani
Luminous Fast Blue Optical Transients (LFBOTs) - the prototypical example being AT 2018cow - are a rare class of events
whose origins are poorly understood. They are characterised by rapid evolution, featureless blue spectra at early times, and
luminous X-ray and radio emission. LFBOTs thus far have been found exclusively at small projected offsets from star-forming
host galaxies. We present Hubble Space Telescope, Gemini, Chandra and Very Large Array observations of a new LFBOT,
AT 2023fhn. The Hubble Space Telescope data reveal a large offset (> 3.5 half-light radii) from the two closest galaxies, both
at redshift 𝑧 ∼ 0.24. The location of AT 2023fhn is in stark contrast with previous events, and demonstrates that LFBOTs can
occur in a range of galactic environments.
The JWST Discovery of the Triply-imaged Type Ia “Supernova H0pe” and Observat...Sérgio Sacani
A Type Ia supernova (SN) at z = 1.78 was discovered in James Webb Space Telescope Near Infrared
Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165; z = 0.35). The SN is situated 1.5–
2 kpc from its host galaxy Arc 2 and appears in three different locations as a result of gravitational
lensing by G165. These data can yield a value for Hubble’s constant using time delays from this
multiply-imaged SN Ia that we call “SN H0pe.” Over the entire field we identified 21 image multiplicities,
confirmed five of them using Near-Infrared Spectrograph (NIRspec), and constructed a new
lens model that gives a total mass within 600 kpc of (2.6 ± 0.3) × 1014M⊙. The photometry uncovered
a galaxy overdensity at Arc 2’s redshift. NIRSpec confirmed six member galaxies, four of which
surround Arc 2 with relative velocity ≲900 km s−1 and projected physical extent ≲33 kpc. Arc 2
dominates the stellar mass ((5.0±0.1)×1011M⊙), which is a factor of ten higher than other members
of this compact galaxy group. These other group members have specific star formation rates (sSFR)
arXiv:2309.07326v1 [astro-ph.GA] 13 Sep 2023
2 Frye, Pascale, Pierel et al.
of 2–260 Gyr−1 derived from the Hα-line flux corrected for stellar absorption, dust extinction, and slit
losses. Another group centered on the dusty star forming galaxy Arc 1 is at z = 2.24. The total SFR
for the Arc 1 group (≳400M⊙ yr−1) translates to a supernova rate of ∼1 SNe yr−1, suggesting that
regular monitoring of this cluster may yield additional SNe.
Hubble Asteroid Hunter III. Physical properties of newly found asteroidsSérgio Sacani
Context. Determining the size distribution of asteroids is key to understanding the collisional history and evolution of the inner Solar System. Aims. We aim to improve our knowledge of the size distribution of small asteroids in the main belt by determining the parallaxes of newly detected asteroids in the Hubble Space Telescope (HST) archive and subsequently their absolute magnitudes and sizes. Methods. Asteroids appear as curved trails in HST images because of the parallax induced by the fast orbital motion of the spacecraft. Taking into account the trajectory of this latter, the parallax effect can be computed to obtain the distance to the asteroids by fitting simulated trajectories to the observed trails. Using distance, we can obtain the absolute magnitude of an object and an estimation of its size assuming an albedo value, along with some boundaries for its orbital parameters. Results. In this work, we analyse a set of 632 serendipitously imaged asteroids found in the ESA HST archive. Images were captured with the ACS/WFC and WFC3/UVIS instruments. A machine learning algorithm (trained with the results of a citizen science project) was used to detect objects in these images as part of a previous study. Our raw data consist of 1031 asteroid trails from unknown objects, not matching any entries in the Minor Planet Center (MPC) database using their coordinates and imaging time. We also found 670 trails from known objects (objects featuring matching entries in the MPC). After an accuracy assessment and filtering process, our analysed HST asteroid set consists of 454 unknown objects and 178 known objects. We obtain a sample dominated by potential main belt objects featuring absolute magnitudes (H) mostly between 15 and 22 mag. The absolute magnitude cumulative distribution logN(H > H0) ∝ αlog(H0) confirms the previously reported slope change for 15 < H < 18, from α ≈ 0.56 to α ≈ 0.26, maintained in our case down to absolute magnitudes of around H ≈ 20, and therefore expanding the previous result by approximately two magnitudes. Conclusions. HST archival observations can be used as an asteroid survey because the telescope pointings are statistically randomly oriented in the sky and cover long periods of time. They allow us to expand the current best samples of astronomical objects at no extra cost in regard to telescope time.
This document presents the target selection process for the first year of the Breakthrough Listen search for intelligent life using the Green Bank Telescope, Parkes Telescope, and Automated Planet Finder. The targets include: 1) The 60 nearest stars within 5.1 parsecs to search for faint signals; 2) 1649 stars spanning stellar types from the Hipparcos catalog; 3) 123 nearby galaxies representing different morphological types to search billions of stars simultaneously; and 4) several classes of exotic objects like white dwarfs and neutron stars. The telescopes will observe 1,000,000 stars and galaxies at radio and optical wavelengths between 350 MHz to 100 GHz and 374-950nm, respectively, to search for technological signals.
Two temperate Earth-mass planets orbiting the nearby star GJ 1002Sérgio Sacani
We report the discovery and characterisation of two Earth-mass planets orbiting in the habitable zone of the nearby M-dwarf GJ 1002 based on
the analysis of the radial-velocity (RV) time series from the ESPRESSO and CARMENES spectrographs. The host star is the quiet M5.5 V star
GJ 1002 (relatively faint in the optical, V ∼ 13.8 mag, but brighter in the infrared, J ∼ 8.3 mag), located at 4.84 pc from the Sun.
We analyse 139 spectroscopic observations taken between 2017 and 2021. We performed a joint analysis of the time series of the RV and full-width
half maximum (FWHM) of the cross-correlation function (CCF) to model the planetary and stellar signals present in the data, applying Gaussian
process regression to deal with the stellar activity.
We detect the signal of two planets orbiting GJ 1002. GJ 1002 b is a planet with a minimum mass mp sin i of 1.08 ± 0.13 M⊕ with an orbital period
of 10.3465 ± 0.0027 days at a distance of 0.0457 ± 0.0013 au from its parent star, receiving an estimated stellar flux of 0.67 F⊕. GJ 1002 c is a
planet with a minimum mass mp sin i of 1.36 ± 0.17 M⊕ with an orbital period of 20.202 ± 0.013 days at a distance of 0.0738 ± 0.0021 au from
its parent star, receiving an estimated stellar flux of 0.257 F⊕. We also detect the rotation signature of the star, with a period of 126 ± 15 days. We
find that there is a correlation between the temperature of certain optical elements in the spectrographs and changes in the instrumental profile that
can affect the scientific data, showing a seasonal behaviour that creates spurious signals at periods longer than ∼ 200 days.
GJ 1002 is one of the few known nearby systems with planets that could potentially host habitable environments. The closeness of the host star
to the Sun makes the angular sizes of the orbits of both planets (∼ 9.7 mas and ∼ 15.7 mas, respectively) large enough for their atmosphere to be
studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission.
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
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Modern astronomers enjoy access to all-sky images across a wide range of the electromagnetic spectrum from
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A Simultaneous dual-site technosignature search using international LOFAR sta...Sérgio Sacani
The Search for Extraterrestrial Intelligence (SETI) aims to find evidence of technosignatures, which
can point towards the possible existence of technologically advanced extraterrestrial life. Radio signals
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Mapping the Skies of Ultracool Worlds: Detecting Storms and Spots with Extrem...Sérgio Sacani
Extremely large telescopes (ELTs) present an unparalleled opportunity to study the magnetism,
atmospheric dynamics, and chemistry of very low mass stars (VLMs), brown dwarfs, and exoplanets.
Instruments such as the Giant Magellan Telescope - Consortium Large Earth Finder (GMT/GCLEF),
the Thirty Meter Telescope’s Multi-Objective Diffraction-limited High-Resolution Infrared Spectrograph
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for longitude and radius are typically . 10◦
, and latitude uncertainties range from ∼ 10◦
to 30◦
.
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First wide field-of-view X-ray observations by a lobster eye focusing telesco...Sérgio Sacani
The document describes the first results from LEIA, a lobster eye X-ray telescope launched as a pathfinder for the Einstein Probe mission. Key results include:
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- Initial analyses found excellent agreement between the observed images and ground cal
Orbital configurations of spaceborne interferometers for studying photon ring...Sérgio Sacani
Recent advances in technology coupled with the progress of observational
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galaxy M87 and the Milky Way Galaxy. The EHT results mark the start of a
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wavelengths. The inclusion of baselines exceeding the diameter of the Earth
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Earth, Sun-Earth L2 and Earth-Moon L2 orbit configurations for the space
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A Search for Technosignatures Around 11,680 Stars with the Green Bank Telesco...Sérgio Sacani
We conducted a search for narrowband radio signals over four observing sessions in 2020–2023 with
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this work, we also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection
and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable
frequency range of the receiver and 98.7% of the injections when regions of dense RFI are excluded. In
another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ∼15 times
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of Merit for SETI search volume calculations that includes the pipeline efficiency and frequency drift
rate coverage. Based on our observations, we found that there is a high probability (94.0–98.7%) that
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signals detected with AI techniques by Ma et al. (2023).
This document summarizes observations of the lensed galaxy HATLAS J142935.3-002836 (H1429-0028) from the Herschel-ATLAS survey. Optical spectroscopy revealed the foreground lens is at redshift 0.218, while the background galaxy is at redshift 1.027. High-resolution imaging from Hubble Space Telescope and Keck adaptive optics show the background galaxy is comprised of two components and a tidal tail, resembling a major merger. Analysis of ALMA observations of CO emission provides a dynamical mass estimate of one component as 5.8 ± 1.7 × 1010 M☉. Modeling of the spectral energy distribution indicates the total stellar mass is 1.32
First Direct Imaging of a Kelvin–Helmholtz Instability by PSP/WISPRSérgio Sacani
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The Large Interferometer For Exoplanets (LIFE) II: Key Methods and TechnologiesAdvanced-Concepts-Team
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WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
GOALS-JWST: Unveiling Dusty Compact Sources in the Merging Galaxy IIZw096Sérgio Sacani
We have used the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) to obtain the first
spatially resolved, mid-infrared images of IIZw096, a merging luminous infrared galaxy (LIRG) at z = 0.036.
Previous observations with the Spitzer Space Telescope suggested that the vast majority of the total IR luminosity
(LIR) of the system originated from a small region outside of the two merging nuclei. New observations with
JWST/MIRI now allow an accurate measurement of the location and luminosity density of the source that is
responsible for the bulk of the IR emission. We estimate that 40%–70% of the IR bolometric luminosity, or
3–5 × 1011 Le, arises from a source no larger than 175 pc in radius, suggesting a luminosity density of at least
3–5 × 1012 Le kpc−2
. In addition, we detect 11 other star-forming sources, five of which were previously
unknown. The MIRI F1500W/F560W colors of most of these sources, including the source responsible for the
bulk of the far-IR emission, are much redder than the nuclei of local LIRGs. These observations reveal the power
of JWST to disentangle the complex regions at the hearts of merging, dusty galaxies.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
VISIONS: The VISTA Star Formation AtlasSérgio Sacani
The VISIONS survey observed five nearby star-forming regions in the near-infrared using the VISTA telescope over a period of 5 years. It collected 1.15 million images totaling 19 TB of raw data. The survey was designed to build an infrared legacy archive similar to 2MASS but probing embedded objects. It used three subsurveys - a wide subsurvey with shallow observations covering large areas, a deep subsurvey targeting regions of high dust extinction, and a control subsurvey of low extinction areas. The goal was to characterize young stellar objects, study stellar and cluster formation and evolution, and measure proper motions to complement the Gaia mission.
Confirmation of the_ogle_planet_signature_and_its_characteristics_with_lens_s...Sérgio Sacani
O Telescópio Espacial Hubble e o Observatório W. M. Keck, no Havaí, fizeram confirmações independentes de um exoplaneta orbitando sua estrela central de uma distância bem grande. O planeta foi descoberto através de uma técnica chamada de microlente gravitacional.
Essa descoberta traz uma nova peça para o processo de caçada de exoplanetas: para descobrir planetas longe de suas estrelas, como Júpiter e Saturno estão do Sol. Os resultados obtidos pelo Hubble e pelo Keck apareceram em dois artigos da edição de 30 de Julho de 2015 do The Astrophysical Journal.
A grande maioria dos exoplanetas catalogados são aqueles localizados bem perto de suas estrelas, isso acontece porque as técnicas atuais de se caçar exoplanetas favorecem a descoberta de planetas com curtos períodos orbitais. Mas esse não é o caso da técnica de microlente gravitacional, que pode encontrar planetas mais frios e mais distantes com órbitas de longo período que outros métodos não são capazes de detectar.
AT2023fhn (the Finch): a Luminous Fast Blue Optical Transient at a large offs...Sérgio Sacani
Luminous Fast Blue Optical Transients (LFBOTs) - the prototypical example being AT 2018cow - are a rare class of events
whose origins are poorly understood. They are characterised by rapid evolution, featureless blue spectra at early times, and
luminous X-ray and radio emission. LFBOTs thus far have been found exclusively at small projected offsets from star-forming
host galaxies. We present Hubble Space Telescope, Gemini, Chandra and Very Large Array observations of a new LFBOT,
AT 2023fhn. The Hubble Space Telescope data reveal a large offset (> 3.5 half-light radii) from the two closest galaxies, both
at redshift 𝑧 ∼ 0.24. The location of AT 2023fhn is in stark contrast with previous events, and demonstrates that LFBOTs can
occur in a range of galactic environments.
The JWST Discovery of the Triply-imaged Type Ia “Supernova H0pe” and Observat...Sérgio Sacani
A Type Ia supernova (SN) at z = 1.78 was discovered in James Webb Space Telescope Near Infrared
Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165; z = 0.35). The SN is situated 1.5–
2 kpc from its host galaxy Arc 2 and appears in three different locations as a result of gravitational
lensing by G165. These data can yield a value for Hubble’s constant using time delays from this
multiply-imaged SN Ia that we call “SN H0pe.” Over the entire field we identified 21 image multiplicities,
confirmed five of them using Near-Infrared Spectrograph (NIRspec), and constructed a new
lens model that gives a total mass within 600 kpc of (2.6 ± 0.3) × 1014M⊙. The photometry uncovered
a galaxy overdensity at Arc 2’s redshift. NIRSpec confirmed six member galaxies, four of which
surround Arc 2 with relative velocity ≲900 km s−1 and projected physical extent ≲33 kpc. Arc 2
dominates the stellar mass ((5.0±0.1)×1011M⊙), which is a factor of ten higher than other members
of this compact galaxy group. These other group members have specific star formation rates (sSFR)
arXiv:2309.07326v1 [astro-ph.GA] 13 Sep 2023
2 Frye, Pascale, Pierel et al.
of 2–260 Gyr−1 derived from the Hα-line flux corrected for stellar absorption, dust extinction, and slit
losses. Another group centered on the dusty star forming galaxy Arc 1 is at z = 2.24. The total SFR
for the Arc 1 group (≳400M⊙ yr−1) translates to a supernova rate of ∼1 SNe yr−1, suggesting that
regular monitoring of this cluster may yield additional SNe.
Hubble Asteroid Hunter III. Physical properties of newly found asteroidsSérgio Sacani
Context. Determining the size distribution of asteroids is key to understanding the collisional history and evolution of the inner Solar System. Aims. We aim to improve our knowledge of the size distribution of small asteroids in the main belt by determining the parallaxes of newly detected asteroids in the Hubble Space Telescope (HST) archive and subsequently their absolute magnitudes and sizes. Methods. Asteroids appear as curved trails in HST images because of the parallax induced by the fast orbital motion of the spacecraft. Taking into account the trajectory of this latter, the parallax effect can be computed to obtain the distance to the asteroids by fitting simulated trajectories to the observed trails. Using distance, we can obtain the absolute magnitude of an object and an estimation of its size assuming an albedo value, along with some boundaries for its orbital parameters. Results. In this work, we analyse a set of 632 serendipitously imaged asteroids found in the ESA HST archive. Images were captured with the ACS/WFC and WFC3/UVIS instruments. A machine learning algorithm (trained with the results of a citizen science project) was used to detect objects in these images as part of a previous study. Our raw data consist of 1031 asteroid trails from unknown objects, not matching any entries in the Minor Planet Center (MPC) database using their coordinates and imaging time. We also found 670 trails from known objects (objects featuring matching entries in the MPC). After an accuracy assessment and filtering process, our analysed HST asteroid set consists of 454 unknown objects and 178 known objects. We obtain a sample dominated by potential main belt objects featuring absolute magnitudes (H) mostly between 15 and 22 mag. The absolute magnitude cumulative distribution logN(H > H0) ∝ αlog(H0) confirms the previously reported slope change for 15 < H < 18, from α ≈ 0.56 to α ≈ 0.26, maintained in our case down to absolute magnitudes of around H ≈ 20, and therefore expanding the previous result by approximately two magnitudes. Conclusions. HST archival observations can be used as an asteroid survey because the telescope pointings are statistically randomly oriented in the sky and cover long periods of time. They allow us to expand the current best samples of astronomical objects at no extra cost in regard to telescope time.
This document presents the target selection process for the first year of the Breakthrough Listen search for intelligent life using the Green Bank Telescope, Parkes Telescope, and Automated Planet Finder. The targets include: 1) The 60 nearest stars within 5.1 parsecs to search for faint signals; 2) 1649 stars spanning stellar types from the Hipparcos catalog; 3) 123 nearby galaxies representing different morphological types to search billions of stars simultaneously; and 4) several classes of exotic objects like white dwarfs and neutron stars. The telescopes will observe 1,000,000 stars and galaxies at radio and optical wavelengths between 350 MHz to 100 GHz and 374-950nm, respectively, to search for technological signals.
Two temperate Earth-mass planets orbiting the nearby star GJ 1002Sérgio Sacani
We report the discovery and characterisation of two Earth-mass planets orbiting in the habitable zone of the nearby M-dwarf GJ 1002 based on
the analysis of the radial-velocity (RV) time series from the ESPRESSO and CARMENES spectrographs. The host star is the quiet M5.5 V star
GJ 1002 (relatively faint in the optical, V ∼ 13.8 mag, but brighter in the infrared, J ∼ 8.3 mag), located at 4.84 pc from the Sun.
We analyse 139 spectroscopic observations taken between 2017 and 2021. We performed a joint analysis of the time series of the RV and full-width
half maximum (FWHM) of the cross-correlation function (CCF) to model the planetary and stellar signals present in the data, applying Gaussian
process regression to deal with the stellar activity.
We detect the signal of two planets orbiting GJ 1002. GJ 1002 b is a planet with a minimum mass mp sin i of 1.08 ± 0.13 M⊕ with an orbital period
of 10.3465 ± 0.0027 days at a distance of 0.0457 ± 0.0013 au from its parent star, receiving an estimated stellar flux of 0.67 F⊕. GJ 1002 c is a
planet with a minimum mass mp sin i of 1.36 ± 0.17 M⊕ with an orbital period of 20.202 ± 0.013 days at a distance of 0.0738 ± 0.0021 au from
its parent star, receiving an estimated stellar flux of 0.257 F⊕. We also detect the rotation signature of the star, with a period of 126 ± 15 days. We
find that there is a correlation between the temperature of certain optical elements in the spectrographs and changes in the instrumental profile that
can affect the scientific data, showing a seasonal behaviour that creates spurious signals at periods longer than ∼ 200 days.
GJ 1002 is one of the few known nearby systems with planets that could potentially host habitable environments. The closeness of the host star
to the Sun makes the angular sizes of the orbits of both planets (∼ 9.7 mas and ∼ 15.7 mas, respectively) large enough for their atmosphere to be
studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission.
Similar to First light of VLT/HiRISE: High-resolution spectroscopy of young giant exoplanets (20)
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
2. A&A proofs: manuscript no. hirise_first_light
et al. 2012; Birkby et al. 2013), before being used to characterize
the direct near-infrared (NIR) emission of young EGPs detected
with high-contrast imaging (Snellen et al. 2014; Schwarz et al.
2016). This method was then generalized to integral-field unit
data to boost the detection capabilities of existing (e.g., Hoeij-
makers et al. 2018) and forthcoming (e.g., Houllé et al. 2021)
instruments.
To combine the potential of high-contrast imaging (HCI)
with HDS for EGPs study, several projects have proposed
to couple existing adaptive optics (AO) instruments with
high-resolution spectrographs using single-mode optical fibers
(SMF). The KPIC instrument on Keck (Delorme et al. 2021) has
been in operation for a few years and has already provided sev-
eral astrophysical results in the K band (e.g., Wang et al. 2021b).
Similarly, the REACH instrument on Subaru is also operational
(Kotani et al. 2020) and providing observations in the H band.
The unit 3 (UT3 – Melipal) of the Very Large Telescope
(VLT) hosts two instruments ideally suited for this purpose. On
one side, the Spectro-Polarimetric High-contrast Exoplanet RE-
search instrument (SPHERE; Beuzit et al. 2019) is attached to
the Nasmyth A focus. On the other side, following the CRIRES+
project (Kaeufl et al. 2004; Dorn et al. 2014, 2023), the upgraded
CRyogenic high-resolution Infra-Red Spectrograph (CRIRES)
was attached to the Nasmyth B focus. HiRISE implements of
a fiber coupling between these two instruments to enable the
characterization of known companions at a spectral resolution
of R ≃ 100 000.
In this paper we present the HiRISE instrument and its per-
formance after commissioning on the VLT. The main astrophysi-
cal requirements and design choices for the system are described
in Sect. 2. Then, in Sect. 3 we present the implementation of the
system, and in Sect. 4 how the system is calibrared and oper-
ated. The on-sky performance and first astrophysical result are
detailed in Sect 5. Finally, we conclude and present some per-
spectives in Sect. 6.
2. Design choices
The idea behind HiRISE is to benefit from the HCI capabilities
of SPHERE and the HDS capabilities of CRIRES to perform the
spectral characterization of known EGPs at high spectral reso-
lution. To guide the overall design of HiRISE, we derived three
astrophysical top-level requirements (TLRs):
sci.req.1 The instrument must enable the direct characteri-
zation of sub-stellar companions, at a significance
higher than 5σ, with integration times shorter than
the duration of 1 night (typically 8 hours).
sci.req.2 The instrument must be more efficient than
CRIRES in standalone for the same science case.
sci.req.3 The instrument must provide access to the H band
and, if possible, to the K band.
These requirements have been explored in details by Otten
et al. (2021) based on a preliminary design of HiRISE. They
demonstrated, in particular, that the overall transmission of the
system is a driving parameter of the final performance. Their
analysis showed that sci.req.1 is easily satisfied for bright
stars (H < 7) and faint companions: typical exposure times of
two to three hours are sufficient to detect companions even at
very high contrast, such as 51 Eri b (Macintosh et al. 2015). They
also showed that in H band, there is a clear part of the contrast
vs. angular separation parameter space where HiRISE signifi-
cantly outperforms CRIRES in standalone, therefore satisfying
sci.req.2. In K band, the noise budget is dominated by the
thermal emission of both the sky and the instruments, which lim-
its the performance of HiRISE.
The choice between H and K band has strong instrumen-
tal implications. The preliminary design considered by Otten
et al. (2021) did not include any active cooling of the instru-
ment, which is the reason why K band is dominated by thermal
background. Cooling the HiRISE module in SPHERE, and pos-
sibly the one in CRIRES, would add major constraints on the
design of the instrument, which would need to include cryostats
that take a lot of space, weight, and complexity. These cryostats
would also not decrease the sky background, which would still
be a major contributor to the noise budget.
The K band is also constraining from the point of view of
optical fibers. Classical telecom fibers made of extremely pure
fused silica are highly transmissive below 1.7–1.8 µm. Beyond
that, their attenuation quickly increases making them unsuitable
for K band and lengths longer than a few meters. Fluoride glass
fibers (often referred to as ZBLAN fibers) are optimized for
longer wavelengths but usually come at a high price and have
a reputation of being difficult to work with, driving up the costs
and manufacturing risks. Based on discussions with the French
manufacturer Le Verre Fluoré, the preliminary design of HiRISE
considered using ZBLAN fibers that would enable observations
in both H and K band. However, Otten et al. (2021) demonstrated
that even with such fibers, CRIRES in standalone would remain
more efficient than HiRISE in K band, and sci.req.2 would
therefore not be satisfied. Following this study, the K band was
abandoned and the design of HiRISE was optimized for the H
band by using highly transmissive telecom fibers.
In the final design, sci.req.3 is therefore only partly sat-
isfied. From the astrophysical point of view, the K band is par-
ticularly interesting due to the prominent CO features starting
around 2.3 µm. Other species, such as H2O or CH4 also have
signatures in the K band, but they are much weaker and dom-
inated by the CO. On the contrary, C- and O-bearing species
have more balanced absorption features in the H band, which
makes this wavelength range interesting to study. Moreover, fu-
ture detections coming from the combination of radial velocity
and ESA/Gaia astrometry (e.g., Rickman et al. 2022) will prob-
ably be older and colder than currently known EGPs, possibly
exhibiting bluer colors with a peak emission in the H or even J
band. This makes the H band particularly interesting for HiRISE
on the long term.
HiRISE uses single-mode fibers (SMF) instead of multimode
fibers (MMF). This choice was driven by the spatial filtering
properties of SMF (e.g., Coudé du Foresto 1994; Patru et al.
2008). In the context of HCI, Mawet et al. (2017) have demon-
strated the significant gain in contrast that is obtained “for free”
due to the poor projection of residual atmospheric phase onto the
mode of the fiber compared to the projection of a well centered
planetary point-spread function (Jovanovic et al. 2015). The use
of SMF also significantly reduces the impact of modal noise, fo-
cal ratio degradation, and transmission of thermal background.
However, SMF induce strong constraints in terms of centering
of the planetary PSF on the fiber, which requires using carefully
calibrated centering strategies (El Morsy et al. 2022).
The very small core of SMF, typically 4–8 µm for telecom
fibers, also implies that connectors should be avoided to reduce
flux losses. For a fiber with a 6 µm core, a decentering of only
0.5 µm between two connected fibers will induce a loss of the or-
der of 10% in the transmitted flux (0.46 dB). And this is without
Article number, page 2 of 17
3. A. Vigan et al.: First light of VLT/HiRISE
even considering Fresnel losses at the interface between the two
fibers. In HiRISE, although connectors were initially considered
to simplify the installation of the fiber bundle, they were eventu-
ally dropped due to the technical challenge of reducing losses to
less than 0.1 dB, or even 0.2 dB.
3. System implementation
At high level, the system is composed of three distinct parts:
(i) the fiber injection module (FIM) implemented in SPHERE
(Sect. 3.1), (ii) the fiber bundle (FB) that links SPHERE and
CRIRES around the UT3 (Sect. 3.2), and (iii) the fiber extraction
module (FEM) installed in CRIRES (Sect. 3.3).
However, both SPHERE and CRIRES are standalone VLT
instruments that are operated independently. They have their
own design choices, constraints, and operational models. From
these considerations, we derived three technical TLRs that drove
the technical design of HiRISE:
tech.req.1 The instrument must not impact regular opera-
tions of SPHERE, CRIRES, or VLT-UT3 when it
is not used.
tech.req.2 The instrument must not require any modifica-
tion of the hardware used in regular SPHERE and
CRIRES operations.
tech.req.3 The instrument must be compatible, as much as
possible, with ESO and VLT standards.
The following subsections describe the different parts of the
system and how the above technical TLRs were satisfied for each
of them.
3.1. Fiber injection module
3.1.1. Opto-mechanical implementation
The FIM is implemented inside the SPHERE instrument, more
specifically in the NIR arm that feeds the IFS. The opto-
mechanical design of the FIM is illustrated in Fig. 1, where the
main components are highlighted. A more detailed view of the
optical design for the FIM is available in El Morsy et al. (2022,
their Fig. 1).
For the opto-mechanical design of the FIM, one of the main
aspect was to strictly satisfy tech.req.1 and tech.req.2.
Since there was no space available upstream of the dichroic fil-
ter that separates the NIR beams between IRDIS and IFS, the
FIM is located in the IFS arm, just after the IFS Lyot stop wheel
where a flat space is available on the common path interface
(CPI) bench. This space was however not sufficient to accommo-
date the optical design without requiring several folding mirrors,
which is why the FIM bench was implemented vertically over
a dedicated interface plate. The IFS beam, which has a diame-
ter of less than 10 mm, goes through the brackets that support
the FIM bench without being vignetted. The CPI interface plate
is attached to the CPI with five screws using existing threaded
holes that were originally used for SPHERE alignment tools. To
satisfy tech.req.3 for SPHERE and minimize stray light re-
flections, mechanical parts close to optical beams were anodized
with an inorganic material, which is black both in the visible and
in the near-infrared.
When using HiRISE, a pick-off mirror is inserted into the
IFS beam with a precision linear stage. Because the stage inserts
an optical element that interacts with the SPHERE beam, the
stage is connected to the existing SPHERE RMC controllers and
controlled through the SPHERE control software. To maximize
compatibility with old RMC controllers and tech.req.3, the
selected stage is identical to existing hardware in SPHERE.
After the pick-off mirror, a single lens is then used to reimage
the pupil of SPHERE onto a flat mirror glued on a piezo tip-tilt
platform1
. The beam is then reflected towards the “optics cube”,
which contains a recollimating doublet, a dichroic plate inclined
at 45◦
, and the air-gapped injection doublet that focuses the beam
in the focal plane where the FB is located (science channel). The
dichroic plate is a custom element manufactured by Fresnel In-
stitute in Marseille (France), which includes a dichroic filter on
the first face and an anti-reflection (AR) coating on the second
face. It reflects more than 80% of the light from 0.95 to 1.25 µm
towards the tracking channel, and transmits more than 98% of
the light from 1.45 to 1.85 µm towards the science channel. All
the other optics in the cube are custom lenses manufactured by
Optiques Fichou (France), and include AR coatings optimized
for the H band.
The tracking channel includes an off-the-shelf lens and mir-
ror to produce a focal plane at F/∼30. The tracking camera is a
C-RED 2 manufactured by First Light Imaging (FLI), which is
based on a Snake InGaAs detector (Feautrier et al. 2017). The
camera is cooled using dedicated cooling lines that were added
as part of the HiRISE installation. This allows cooling the de-
tector down to −20◦
C without using the need of any fan, there-
fore avoiding any vibrations on the SPHERE bench. With 15 µm
pixels, the tracking camera is Nyquist-sampled at 0.99 µm, just
slightly above the start of our working spectral range at 0.95 µm.
A third channel, the feedback channel, is also implemented.
It is used to retro-inject light from dedicated feedback fibers in
the FB into the FIM and project their image over the tracking
image on the camera. The beam goes backwards through the in-
jection doublet, reflects on the dichroic plate, then reflects in a
corner cube, and is finally transmitted again through the dichroic
plate before joining the tracking channel. A compensator lens
was added just before the corner cube to compensate for differ-
ences in the longitudinal chromatism of the feedback and track-
ing channels. The wavelength of the calibration source has been
selected at 1.3 µm to be in the transition region of the dichroic
function: since the feedback signal sees the dichroic function
twice, it is important to select a wavelength where the signal
will not be significantly attenuated. At 1.3 µm, approximately
10% of the feedback signal is transmitted towards the tracking
camera. For more details on the purpose of the feedback fibers,
see Sect. 4 and El Morsy et al. (2022).
The optical quality of the FIM was estimated using a com-
mercial NIR wavefront sensor from Phasics S.A. A total of
∼50 nm rms was measured on-axis after alignment of the sys-
tem on a “SPHERE simulator” reproducing the SPHERE IFS
beam in the laboratory. The error budget is mainly dominated
by a combination of astigmatism and spherical aberrations that
could not be minimized during assembly, integration and testing
(AIT) in Europe. Off-axis, the wavefront error increases up to
80–100 nm rms at the edge of the useful FIM field-of-view (FoV)
of ∼1.5′′
. Beyond 1.5′′
, Otten et al. (2021) have demonstrated
that CRIRES in standalone is likely more efficient than HiRISE
for the same science cases. After installation on SPHERE, a new
measurement was performed with the same wavefront sensor,
and a value of ∼70 nm rms was measured on-axis, this time in-
cluding the contribution of the SPHERE CPI optics. This is com-
patible with previous results reporting between 50 and 60 nm rms
1
An S-335 piezo tip/tilt platform from Physik Instrumente (PI), with
the E-727 controller.
Article number, page 3 of 17
4. A&A proofs: manuscript no. hirise_first_light
IRDIS
SAXO
IFS Lyot
stop wheel
Tracking
camera
Pick-off
mirror
Core optics
bench Fiber
mount
Tip-
tilt
Corner cube
Optics
cube
CPI interface
Fig. 1. Implementation of the FIM inside the IFS arm of SPHERE. On the left drawing, the SPHERE components are labelled in black, while the
FIM components are labelled in red. The inset in the top right shows the components of the core optics bench. The light path in the system is fully
illustrated in Vigan et al. (2022b, their Fig. 3). The picture on the right shows the FIM at the end of the installation in SPHERE. The IFS Lyot
wheel is visible in the bottom left of the picture.
Electronics cabinet
Control room
Direct connection
1 GB/s network
Ethernet switch
Service connection
10 GB/s network
HiRISE
workstation
PLC
Power-meter
Light
sources
Temperature
probes
Web power
switch
Tracking
camera
Frame
grabber
FIM
User
workstation
Tip-tilt
piezo stage
Tip-tilt
controller
Fig. 2. Connection mapping between the electronics cabinet, the different devices, and the control network that is used to operate the instrument
from the control room.
of aberrations in the SPHERE instrument (N’Diaye et al. 2016;
Vigan et al. 2019, 2022a).
Conceptually, the FB remains static with respect to the FIM,
and it is the science image that is moved with respect to the fibers
using the tip-tilt mirror. The PI S-335 stage offers a tip-tilt angle
of ±17.5 mrad (±1◦
) with a resolution in closed-loop of 1 µrad
and a linearity of 0.05%. During AIT and commissioning at the
VLT, we measured a conversion factor of ∼42.2 pix/mrad be-
tween the tip-tilt mirror and the tracking camera. At F/30 and
with pixels of 15 µm on the tracking camera, we therefore have
the equivalence of 1 λ/D = 3.22 pix = 76 µrad at λ = 1.6 µm.
The work of El Morsy et al. (2022) showed that the specification
on the centering of the PSF on the science fiber should be better
than 0.1 λ/D to reach the best performance, which corresponds
to 7.6 µrad. This is well within the accuracy of 1 µrad that is
typically offered by the tip-tilt platform.
3.1.2. Electronics cabinet
The FIM includes several active components that need to be con-
trolled to operate the instrument. For this purpose, a new dedi-
cated electronics cabinet has been implemented on the SPHERE
Nasmyth platform below the SPHERE enclosure near IRDIS.
This location has the advantage of leaving space for maintenance
(tech.req.1) and of being exactly underneath the cable feed-
through that is closest to the FIM.
The cabinet embeds all the elements necessary to control, op-
erate and calibrate the FIM and the FEM (Fig. 2). One of the key
Article number, page 4 of 17
5. A. Vigan et al.: First light of VLT/HiRISE
elements of the cabinet is the HiRISE workstation running Linux
and the 2020 release of the VLT Software. The workstation is a
fan-less industrial computer used for embedded applications. It
is connected to the VLT control network through a Cisco switch
that is also embedded in the cabinet.
For the operations and calibrations, the cabinet includes a
broadband halogen light source used by the FEM (see Sect. 3.3),
a LED light source at 1.3 µm used for the feedback fibers, a
power-meter coupled with an InGaAs photodiode (see Sect. 4),
two Pt100 temperature sensors (one in the cabinet and one on
the core optics bench of the FIM), the controller for the piezo
tip-tilt stage, and a Camera Link-to-GigE frame grabber2
to ac-
quire frames from the tracking camera.
The iPort CL-Ten frame grabber was selected as it is sup-
ported in the VLT Software based on developments done for the
NIRPS instrument (Bouchy et al. 2017; Wildi et al. 2017). It
converts the Camera Link signal into the GigE Vision standard,
which is transmitted directly to the HiRISE workstation over a
10 GB Ethernet optical link connected to a dedicated network
interface.
The light sources, temperature probes, and power-meter
are connected to and controlled by a Beckhoff CX2100 pro-
grammable logic controller (PLC) that follows the most recent
ESO standards for VLT instrumentation. The PLC is connected
to the workstation through the HiRISE network switch.
The piezo tip-tilt stage controller is also connected to the net-
work switch and is controlled over TCP/IP using the dedicated
General Command Set (GCS) from PI.
Finally, the cabinet also has multiple power sockets, includ-
ing three that are controlled through a web power switch, which
is connected to the network switch and can be activated from the
workstation. The tracking camera and frame grabber are both
connected to this controllable power socket to be able to re-
motely perform power cycles and to power them down when the
instrument is not in use.
3.2. Fiber bundle
The FB of HiRISE is a single piece of hardware that routes sci-
ence and calibration fibers from SPHERE to CRIRES. It was
manufactured by FiberTech Optica (Canada). It has a total length
of 83.9 m, divided into three sections: a short section in SPHERE
(2.5 m), a long section around the telescope (78.2 m), and an-
other short section in CRIRES (3.2 m). A conceptual drawing of
the FB with its input and output ferrules is presented in Fig. 3.
The choice of science fiber was based on its operating wave-
length, its numerical aperture (NA), and its transmission in H
band. Originally, the optical design of HiRISE was consider-
ing off-the-shelf ZBLAN fibers proposed from manufacturer Le
Verre Fluoré, which had NA = 0.16. When it was finally de-
cided to drop the ZBLAN fibers for more standard telecom
fibers, the closest match on the market in terms of NA was found
to be the Nufern 1310M-HP fiber. The specifications of that
fiber are summarized in Table 1. The attenuation of this fiber
is ≤ 0.50 dB/km at 1.550 µm, which translates into an expected
transmission ≥ 0.989 for a 100 m fiber. Beyond 1.6 µm, the at-
tenuation is expected to rise, but laboratory measurements per-
formed during the design phase of HiRISE with a 100 m sample
showed that the transmission remains higher than 0.97 at 1.8 µm,
which is the upper limit of our spectral range for science.
For science, the bundle has four fibers: one that samples the
planetary signal at the center of the FoV (science fiber), and three
2
The iPort CL-Ten from Pleora Technologies.
that sample the PSF or speckle field of the star in the field (refer-
ence fibers). These four fibers go all the way from the input fer-
rule in SPHERE to the output ferrule in CRIRES. Pictures of the
ferrule and input/output fiber arrangements are shown in Fig. 4.
The ferrules are made of Invar to avoid stresses due to tempera-
ture variations. In both ferrules, the mechanical center is located
within a few micrometers of the center of the science fiber. The
fibers are in a packed geometry where they touch cladding-to-
cladding, so the cores are located 125 µm apart from each other.
To maximize the transmission at the input and output, the fer-
rules are AR-coated with coatings optimized up to 1.850 µm on
both sides. The lower limit for the AR-coating is different on the
input and output for reasons that will be detailed below.
For operations and calibrations on the SPHERE side, the in-
put ferrule includes five calibration fibers. Four of them are the
feedback fibers described in Sect. 3.1, which are connected to a
LED light source in the electronics cabinet. The fifth one, called
the centering fiber, is connected to a power-meter in the cabinet
and is used for the target acquisition in the FIM (see Sect. 4).
On the CRIRES side, two side fibers are placed on the same
line as the science and reference fibers to mark the starting and
ending positions. These fibers have been used only during AIT
at the telescope to help find the orientation of the CRIRES dero-
tator that aligns the science fibers with the spectrograph’s slit.
For this purpose they were temporarily connected to an indepen-
dent halogen source. Two additional fibers are dedicated to AO
calibrations for the CRIRES MACAO system (Paufique et al.
2004). One is an SMF identical to the science fibers, and the
other is an MMF with a 50 µm core, NA = 0.22 and an operating
wavelength range of 350–2400 nm. These guide fibers are used
to create a reference for the MACAO wavefront sensor (WFS)
and maintain the MACAO deformable mirror (DM) flat during
HiRISE observations. More explanations on these aspects are
provided in Sect. 4. The MMF fiber was included in case the flux
coming from the calibration source through the SMF guide fiber
would be too low for MACAO, but tests at the telescope showed
that the light coming from the SMF is sufficient for MACAO
operations.
The fibers are protected within a PVC-coated stainless in-
terlock monocoil conduit. The short SPHERE and CRIRES sec-
tions, which require more flexibility, have an outer diameter of
4.2 mm, while the long central section has an outer diameter of
9.2 mm. Inside the long central section the fibers are protected
into an additional internal PVC furcation tubing, reinforced with
Kevlar thread, and a glass fiber tensile core to decrease mechan-
Table 1. Specifications of the Nufern 1310M-HP fiber
Parameter Value
Optical specifications
Operating wavelength 1310–1620 nm
Core numerical aperture 0.16
Mode field diameter 6.7 ± 0.5 µm @ 1310 nm
7.6 ± 0.6 µm @ 1550 nm
Cutoff wavelength 1250 ± 50 nm
Core attenuation ≤ 0.75 dB/km @ 1310 nm
≤ 0.50 dB/km @ 1550 nm
Geometrical & mechanical specifications
Cladding diameter 125 ± 1.0 µm
Core diameter 6.0 µm
Core/cladding offset ≤ 0.5 µm
Bend radius ≥ 6 mm [short term]
≥ 13 mm [long term]
Article number, page 5 of 17
6. A&A proofs: manuscript no. hirise_first_light
Calibration fibers
with FC connectors
Telescope
78.2 m
SPHERE
2.5 m
CRIRES+
3.2 m
Input geometry
AR coated 1250-1850 nm
Output geometry
AR coated 800-1850 nm
Science
fi
ber
Reference
fi
bers
Dummy
fi
bers
Side
fi
bers
Centering
fi
ber
AO MMF guide
fi
ber
Feedback
fi
bers
AO SMF guide
fi
ber
Spectral
dispersion
Fig. 3. Conceptual drawing of the FB. Only four fibers (science and references) go all the way from the input ferrule to the output ferrule. The
other fibers are for calibration or AIT, or simply dummy fibers filling the geometrical patterns in the ferrules. All calibration fibers enter or exit
the bundle at the level of the junction between the SPHERE and telescope sections. The SPHERE and CRIRES sections have a smaller diameter
(4.8 mm) and are more flexible than the central telescope section (9.2 mm), which is reinforced. All fibers are identical Nufern 1310M-HP SMF,
except for the AO MMF guide fiber that is multimode with a 50 µm core.
Fig. 4. Picture of the input ferrule of the FB on the left. The blue and purple colors at the surface of the ferrule are due to the AR coating that was
applied to minimize Fresnel losses. The center and right pictures show the input and output patterns of fibers, respectively, obtained by imaging
the ferrules under a binocular magnifier. In both cases, the science and reference fibers are lit up by illuminating the other ferrule using a halogen
lamp. Some reflections and scratches are visible on the surface of both ferrules. The fibers that are not lit up correspond either to calibration fibers
that were not illuminated when taking the pictures or to dummy fibers used to pack the geometry of the pattern (see Fig. 3). The fiber that appear
damaged at the bottom right of the output ferrule is a dummy fiber that has no functional purpose.
ical stress when the outside temperature changes. The central
section has two stainless steel breakouts at both ends, which re-
inforce the junctions with the short SPHERE and CRIRES sec-
tions. On the SPHERE side, the breakout also lets the ancillary
calibration fibers go in and out.
The FB was routed around the UT3, starting on the SPHERE
side, using existing cable ducts. The route follows cable ducts
underneath the azimuth platforms, then follows the telescope
structure to reach the inner track of the telescope under the az-
imuth floor. An electrical cable with approximately the same
minimum radius of curvature as the FB was installed in 2021 to
measure the exact length required for the bundle. Another possi-
ble shorter route would have been to follow the primary mirror
cell, but in that case the bundle would have needed to be included
in the altitude cable wrap of the telescope and would have been
subject to constant stresses as the telescope is operated. The se-
lected path is therefore slightly longer, but the bundle remains
entirely static once it is installed.
3.3. Fiber extraction module
The FEM is a much simpler system than the FIM. It is located
in the calibration carrier stage of CRIRES, which is at the en-
trance of the warm bench of the instrument. The edge of the
carrier stage lies within a couple of centimeters of the VLT fo-
cal plane. The warm bench contains the instrument derotator, the
MACAO deformable mirror, and the MACAO wavefront sensor
(Dorn et al. 2023; Paufique et al. 2004). It produces a turbulence-
corrected image in the plane of the slit located at the entrance of
the spectrograph.
Article number, page 6 of 17
7. A. Vigan et al.: First light of VLT/HiRISE
Calibration
carriage stage
Gas cells
FEM
Telescope
Spectro.
Ferrule
support
Fig. 5. Implementation of the FEM on the calibration carriage stage at the entrance of CRIRES. On the left drawing, existing CRIRES components
are labelled in black, while the FEM is labelled in red. The inset in the top left shows the inside of the FEM. The output ferrule of the FB is inserted
vertically from the top in the ferrule support. The picture on the right shows the FEM after its installation in CRIRES. The FB (black-coated with
a white sticker) is visible over the FEM.
The purpose of the FEM is to reimage the fibers in the output
ferrule, which have a focal ratio of F/3.5, into the VLT focal
plane at F/15 and with a pupil image at the distance of the UT3
pupil. It is composed of a total of four lenses (including a glued
doublet). A flat folding mirror is used to make the system more
compact and to ensure that the ferrule is inserted from the top to
avoid unnecessary bending of the fibers. All lenses are custom-
made by Optiques Fichou and AR-coated from 0.8 to 1.85 µm
to cover the science wavelengths as well as the red part of the
visible for the calibration of MACAO using one of the AO guide
fibers in the FB.
The mechanical design of the FEM allows it to fit within the
space allocated for visitor gas cells (tech.req.2) where it does
not impact the regular operations of CRIRES (tech.req.1).
Moreover, the FEM has been designed to be easily removed in
case of an observing run requiring a visitor gas cell or during
technical interventions. A drawing and picture of the implemen-
tation is visible in Fig. 5. Contrary to the FIM, the mechanical
parts of the FEM have not been anodized due to a lack of time
during AIT.
4. Operations
The operations of HiRISE involve three instruments: SPHERE,
the HiRISE FIM, and CRIRES. In this section we describe the
necessary calibrations before HiRISE observations (Sect. 4.1),
the science target acquisition (Sect. 4.2), and the science obser-
vations (Sect. 4.3).
During commissioning, the operations were done with a
mix of existing VLT software templates, a couple of templates
developed specifically for HiRISE, and python scripts calling
VLT software functions to control hardware. This situation may
evolve in the future towards only templates to make the instru-
ment operable on a regular basis by the observatory personnel.
4.1. Calibrations
A series of calibrations are performed before the beginning of
the night to prepare for the observations. All the calibrations be-
low are performed using only the SPHERE internal light sources,
which allows doing them during the afternoon preceding obser-
vations. We report here the status of calibrations after commis-
sioning, but we note that they may evolve in the future as we
learn more about the instrument.
4.1.1. Calibrations involving only SPHERE and the FIM
The first calibration aims at determining the linear coefficients
of the tip-tilt angular motion of the FIM mirror in relation to
the PSF motion on the tracking camera detector. The working
range of tip-tilt is typically ∼4 mrad with respect to the reference
position determined during commissioning. Over this range, the
PSF moves by 42.1 and 42.3 pix/mrad in tip and tilt, respectively.
Deviations from linearity remain below 0.2 pix (0.06 λ/D at λ =
1.6 µm) in the working range.
The second calibration aims at determining the coefficient
of the interpolation function previously presented by El Morsy
et al. (2022). The goal of this calibration is to provide a tool
that allows placing the PSF at any desired position on the track-
ing camera detector. This calibration is performed by recording
the position of the PSF for a grid of tip and tilt values on the
mirror. The recorded positions are then fed to an interpolation
function (currently LinearNDInterpolator from the scipy
python package), which returns two functions. These functions
take as parameter a desired position in pixel coordinates on the
tracking camera and return the commands in tip and tilt, respec-
tively, to be applied to the mirror to bring the science PSF at
the desired location. Immediately after the calibration, the PSF
can be placed at the desired location with an accuracy typically
better than 0.1 pix (0.03 λ/D at λ = 1.6 µm), but temporal drifts
related to temperature changes in SPHERE have been observed,
which decrease the accuracy. A more thorough analysis will be
Article number, page 7 of 17
8. A&A proofs: manuscript no. hirise_first_light
1.2 1.3 1.4 1.5
Tip [mrad]
0.8
0.7
0.6
0.5
Tilt
[mrad]
10 2
10 1
100
Normalized
intensity
Fig. 6. Example of a 20×20 pixels injection map done on the centering
fiber with the power-meter. The sampling of 0.02 mrad/pixel (0.5 λ/D
at λ = 1.6 µm) is relatively coarse but sufficient to obtain an accurate
estimate of the center position with a gaussian fit (black cross). The spot
is extended along one of the diagonals because of the projection effect
of the pupil on the tip-tilt mirror, which tilted by 45◦
.
presented in El Morsy et al. (in prep.). The loss of absolute accu-
racy is not critical for operations, as will be explained in Sect. 4.2
on the target acquisition.
The third calibration is to build interaction and command
matrices for the tip-tilt mirror. The interaction matrix is cali-
brated by moving it in tip and tilt by a fixed amount of 0.5 mrad,
starting from a position close to that of the science fiber, and
recording the motion of the PSF on the tracking camera detec-
tor. Then the command matrix is computed and allows moving
the PSF by small amounts for corrections during target acquisi-
tion and observations. The command matrix is used as a com-
plement to the interpolation function described in the previous
paragraph. The accuracy of the motions based on the command
matrix is typically better than 0.1 pix (0.03 λ/D at λ = 1.6 µm).
Then we record an injection map on the centering fiber. In-
jection maps are obtained by scanning the science PSF in front
of a fiber using the tip-tilt mirror and recording the output flux at
the other end of the fiber by means of a camera or power-meter
(e.g., El Morsy et al. 2022). The goal is to determine the po-
sition of the fiber in tip-tilt space, i.e. the tip-tilt command that
allows centering the stellar PSF on the fiber. In HiRISE, we use a
centering fiber connected to a power-meter inside the electronics
cabinet. Power-meters offer the advantage of a very fast readout
(< 1 ms) and relatively good sensitivity in H band with InGaAs
photodiodes. While this sensitivity is not sufficient to perform
on-sky injection maps, except for extremely bright stars, it is
sensitive enough to work on the SPHERE internal source. For
the daily calibration on the centering fiber, we sample a grid of
0.4×0.4 mrad2
20 times in each dimension (400 positions in to-
tal), which produces an injection map in less than 1 min and pro-
vides a good accuracy on the position of the fiber. An example of
daily injection map obtained during commissioning is presented
in Fig. 6.
4.1.2. Calibrations involving CRIRES and MACAO
With the FEM at the entrance of CRIRES, the HiRISE light
goes through the complete instrument (warm bench and spec-
trograph), including the MACAO AO system. Because of its in-
960 980 1000 1020 1040
x [pix]
980
1000
1020
1040
1060
1080
y
[pix]
slit
ao
ref1
science
ref2
ref3
10 4
10 3
10 2
10 1
100
Normalized
intensity
Fig. 7. Slit viewer (SV) camera image of the fibers reimaged by the
FEM. The cross-like diffraction pattern, particularly visible for the AO
guide fiber, is induced by a pupil mask installed on the MACAO DM for
calibrations. The image is done with a closed-loop on MACAO and by
offsetting the center of the guide window on the SV camera so that the
science and reference fibers are moved out of the slit (dashed vertical
lines).
trinsic properties, the MACAO DM cannot remain completely
flat for long periods of time and requires to be used in closed
loop. This is why the FB includes two guide fibers (one SMF,
one MMF) fed by a halogen source: one of these fibers is used
as a guide “star” for the MACAO WFS to work in closed loop
and keep the DM flat and stable during the observations. After
some testing during commissioning, the SMF was considered
sufficient in terms of flux, and it is now the reference fiber for
operations of HiRISE. A picture of the AO guide fiber, fed by
the halogen source, and the science and reference fibers, illumi-
nated by a flat-field source in SPHERE, is shown in Fig. 7. Since
everything is completely static during HiRISE observations, the
MACAO parameters for this guide fiber have been determined
once and do not require to be recalibrated regularly. For this
reason, HiRISE daily calibrations do not require any MACAO-
specific calibrations.
The CRIRES control software also includes a secondary
guiding based on the position of the guide star on the slit viewer
(SV) camera. This guiding ensures that any differential motion
between the warm bench and the cold spectrograph, which are
not physically tied, is compensated during observations. For
HiRISE, the center of the guide window has been calibrated so
that the science and reference fibers fall exactly at the center of
the 0.2′′
slit. Again, the secondary guiding parameters are not
expected to vary over time, so they have only been calibrated
once during commissioning.
The SV secondary guiding offers the possibility to update in
real time the center of the guide window to offset the science and
reference fibers from the slit, and make them become visible on
the SV camera. Figure 7 is obtained in such a configuration, with
the center of the guide window offset by 8 pixels from its refer-
ence position. In this configuration, we calibrate every day the
position of each fiber for flux measurements (see below) by fit-
Article number, page 8 of 17
9. A. Vigan et al.: First light of VLT/HiRISE
0 250 500 750 1000 1250 1500 1750 2000
x [pix]
1300
1400
1500
1600
1700
y
[pix]
Fig. 8. Portion of a trace image on the CRIRES science detector #1, showing the third and fourth spectral order. The image is obtained by
illuminating the science and reference fibers with a flat-field source in SPHERE. This image is used to measure the position the fibers in the
spectral data to facilitate signal extraction.
ting a 2d Gaussian function on the spots. These values are stored
in a local database for later use during the calibrations and ob-
servations.
From the data of Fig. 7, we can estimate the fraction of light
that goes through the slit: 89% for the 0.2′′
slit (baseline for
HiRISE observations), and 96% for the 0.4′′
slit. For the 0.2′′
slit, this estimation is in good agreement with the estimation of
92% from the optical design.
In the offset configuration, it is possible to produce injection
maps on the science fiber by measuring the output flux on the
SV camera. This is, however, much slower than for the centering
fiber because it involves several more steps than simply reading
the output value of a power-meter: image acquisition on the slit
viewer (typically 0.5 to 1 s), image transfer to the HiRISE work-
station (∼1 s), image reading and analysis (∼1 s). This is why
this solution is not used in the daily calibrations and has only
been used a few times during commissioning to check its feasi-
bility. Instead, we use the calibrated offset between the centering
and science fibers (−1.483 mrad in tip, +1.551 mrad in tilt) to
place the PSF on the science fiber after the injection map on the
centering fiber. Then, we run a Nelder-Mead optimization using
the scipy.optimize package to maximize the flux measured
at the output of the science fiber on the SV camera, which is
used as a proxy to maximize the injection in the fiber. The opti-
mization is limited to 10 iterations, or 20 evaluations of the flux
on the SV camera, to minimize the time of the calibration. Al-
though some additional testing would need to be done, we have
not found that a higher number of iterations provides a higher
output flux, which seems to indicate that the centering in 10 iter-
ations is accurate enough. The time required for this calibration
is of the order of 2 minutes: 1 to 1.5 minute for the optimization
algorithm, and twice 15 s to introduce and remove the offset on
the SV guide window.
Finally, the last calibration involves applying the flat-field
source in SPHERE to illuminate the science and reference fibers
(like in Fig. 7), but this time with image of the fibers falling in the
slit and being fed into the spectrograph. This allows producing a
“trace image” where the location of each fiber for each order and
detector is clearly identifiable. This calibration will later be used
in the data analysis when extracting the flux of a companion. A
portion of a trace image is visible in Fig. 8.
4.2. Target acquisition
The science target acquisition is a multistep process. At the be-
ginning of the night, a MACAO specific template is executed
on the HiRISE workstation to set MACAO up, acquire a back-
ground on the SV camera, and close the MACAO and the sec-
ondary guiding loops on the HiRISE AO guide fiber. CRIRES
being used with the fixed constellation of HiRISE fiber bun-
dle, all sky-related controls are made static: off-axis AO track-
ing, derotator angle. In principle, this template can be executed
once per night because the MACAO configuration is static and
the loop can remain closed on the guide fiber for many hours
without any disturbance. However, as we will see in Sect. 5, a
different operational scheme may be necessary in the future. The
execution of this template, which as been developed specifically
for HiRISE, takes less than a minute.
Then, the SPHERE IRDIFS-EXT acquisition template is ex-
ecuted. Briefly speaking, this template sends a preset to the
telescope, set SPHERE up for observation, and optimizes the
SPHERE ExAO system (SAXO). Since we do not use a coron-
agraph with HiRISE to maximize the number of planetary pho-
tons that reach the spectrograph’s detector, the acquisition tem-
plate does not perform any of the additional steps that are typi-
cally required when using a coronagraph such as optimizing fo-
cus and centering. It typically takes between 5 and 10 minutes
depending on telescope preset time and observing conditions.
The final, most critical step, is the centering of the sub-stellar
companion’s PSF on the science fiber at the level of the FIM.
This step is difficult because part of the error budget is tied to the
uncertainties of the on-sky astrometry of the companion coming
from previous observations, over which we have no control. It
is therefore important to be as accurate as possible on the cen-
tering with the FIM to maximize the injection efficiency into the
science fiber.
For better performance, the centering is performed on the
bright internal source of SPHERE, which provides a highly sta-
ble and repeatable PSF. After the target acquisition in SPHERE,
we immediately switch back to the internal source and perform
a fast injection map on the centering fiber to find its approx-
imate location. Then, we offset the guide window of the sec-
ondary guiding on the SV camera of CRIRES to move the sci-
ence and reference fibers out of the slit, we apply the calibrated
offset on the FIM tip-tilt mirror to place the source’s PSF on the
science fiber, and we perform an optimization to accurately cen-
ter the PSF. And finally, we remove the secondary guiding offset
to move back the fiber to the slit. After these steps, we know that
the internal source’s PSF is accurately centered on the science
fiber.
At this stage, a tracking camera image is acquired to define
the corresponding location of the science fiber on the detector.
Article number, page 9 of 17
10. A&A proofs: manuscript no. hirise_first_light
From this and the known astrometry of the companion, we com-
pute the detector location at which the stellar PSF must be placed
so that the companion’s PSF will be centered on the science fiber.
The PSF is then moved to that location using the interpolation
function (see Sect. 4.1). Because of the temporal drifts, the PSF
usually falls within one pixel of the requested location, so we
implement a correction loop using the command matrix to refine
the position. The loop is stopped when the measured position of
the PSF is within 0.05 pixel (0.015 λ/D at λ = 1.6 µm) of the re-
quested position, or when a maximum of 10 iterations have been
performed.
Finally, SPHERE is switched back to skylight to reacquire
the science target. A pause of 90 seconds is added to wait for
the ExAO modal gains to be updated to values adequate for the
current on-sky conditions. Indeed, when switching to the inter-
nal source the modal gains automatically update to a very small
value, of the order of 0.01, because there is no turbulence to cor-
rect.
After switching back to sky, we rely on a major feature of the
SPHERE ExAO system to ensure that the companion’s PSF will
actually be centered on the science fiber: the differential tip-tilt
sensor (Beuzit et al. 2019). This sensor is located just before the
coronagraphic focal-plane masks in the NIR arm of SPHERE. It
picks up a very small fraction of light near the H-band to pro-
duce a PSF on a 32×32 pix detector. A dedicated control loop,
working at 1 Hz, ensures that the PSF remains stable at a po-
sition defined by calibrated reference slopes. The classical role
of the DTTS loop is to maintain the PSF perfectly stable on the
focal-plane mask.
For HiRISE we divert this feature to our advantage: if the
internal source of SPHERE is centered on a given DTTS pixel,
then the DTTS loop ensures that the on-sky stellar PSF will be
centered identically on sky. This means that after the full FIM
centering procedure on the internal source, the stellar PSF will
still fall at the same exact location of the FIM tracking camera,
and the PSF of the sub-stellar companion will still be centered
on the science fiber.
4.3. Observations
The science observations are more straightforward. They are ex-
ecuted using a HiRISE specific template that runs directly on the
HiRISE workstation and sends commands to the CRIRES work-
station for data acquisition.
At the beginning of the template, the internal CRIRES
metrology is run for the user-requested spectral setting. This en-
sures a more accurate wavelength calibration over long observa-
tions. The use of the metrology is highly recommended by the
user manual for any CRIRES observations (see Dorn et al. 2023
for details on the metrology). The metrology is automatically run
in case of change of spectral setting with respect to the previous
observation, or if the previous execution was done more than one
hour before.
HiRISE then sets CRIRES in the relevant configuration:
SPHERE remains in control of all telescope motions, while
CRIRES maintains –internally– the relevant secondary loops ac-
tive. In particular, the SV keeps sending offsets to MACAO,
while differential refraction correction is not active. The offsets
are performed with combined offsets of MACAO field selector
and of its tip-tilt mount, as well as of the SV camera guide win-
dow. Although not mandatory, small offsets between exposures
can be used to avoid having the spectra always falling on the
same bad pixels of the science detectors.
Fig. 9. Screenshot of the tracking camera image obtained after center-
ing a stellar companion on the science fiber (roughly at the center of
the image). The primary star is located upper left of the companion.
The four broad spots forming a square are the images of the feedback
fibers. Their specific size and shape are due to the optics in the feedback
channel of the FIM, and in particular to the use of a corner cube for the
retro-reflection. The center of each feedback fiber is obtained with a 2d
Gaussian fit on the brightest peak of their image.
Finally, science exposures are acquired with a detector inte-
gration time (DIT) specified by the user. The user has the possi-
bility to choose the number of DIT per exposure (NDIT) and the
number of exposures per offset position (NEXP).
During long science observations, a tracking loop is run ev-
ery minute to maintain the companion’s PSF aligned as accu-
rately as possible with the science fiber (Fig. 9). This loop uses
the image of the feedback fibers (Sect. 3.2) on the tracking cam-
era, through the dedicated FIM feedback channel (Sect. 3.1).
AIT and commissioning measurements have demonstrated that
the position of the feedback spots is well correlated with the po-
sition of the image of the centering fiber on the tracking camera
detector (see analysis and caveats in Sect. 5.2 below).
The loop therefore tries to ensure that the image of the stel-
lar PSF remains stable with respect to the crossing point I of
the lines going through opposite feedback points. When a mea-
surement is made in the loop, the distance between I and the
stellar PSF is measured and compared to the distance measured
immediately after the target acquisition. If the distance is above a
predefined threshold (0.05 pix during commissioning), the FIM
tip-tilt mirror is moved using the command matrix to bring the
PSF back to the calibrated distance, in a maximum of 3 itera-
tions. The parameters of this tracking loop will be adjusted in
the future as more experience is gained with HiRISE.
5. Performance
5.1. Astrometry
The astrometric calibration is a crucial aspect for HiRISE be-
cause, in most cases, we rely on known relative astrometry of
sub-stellar companions with respect to their host star to place
their PSF on the science fiber. For HiRISE, the astrometric cal-
ibration relies on close binaries (< 1.5′′
) observed in parallel
with the FIM tracking camera and with SPHERE/IRDIS. IRDIS
astrometric strategy and accuracy has been determined in the
SPHERE GTO and is well documented (Maire et al. 2021). The
cross-calibration with IRDIS is therefore the most straightfor-
Article number, page 10 of 17
11. A. Vigan et al.: First light of VLT/HiRISE
Table 2. Astrometric calibration of HiRISE
IRDIS HiRISE detector HiRISE sky
Target Epoch Sep. sky PA sky Sep. PA Pixel scale North correction
[mjd] [mas] [deg] [pixel] [deg] [mas/pixel] [deg]
HIP 103311 60137.2326 774.11 ± 0.25 317.08 ± 0.04 60.28 ± 0.03 47.35 ± 0.16 12.842 ± 0.008 90.27 ± 0.31
HIP 109344 60137.2498 701.04 ± 0.23 22.06 ± 0.04 54.69 ± 0.03 112.44 ± 0.16 12.818 ± 0.008 90.38 ± 0.21
HIP 65288 60137.9681 761.39 ± 0.25 245.17 ± 0.04 59.67 ± 0.02 335.53 ± 0.15 12.760 ± 0.006 90.36 ± 0.04
HIP 77939 60138.0090 362.80 ± 0.12 111.99 ± 0.04 28.39 ± 0.04 202.40 ± 0.16 12.779 ± 0.019 90.41 ± 0.08
HIP 82460 60138.0694 805.10 ± 0.26 170.27 ± 0.04 62.81 ± 0.04 260.64 ± 0.16 12.818 ± 0.009 90.37 ± 0.06
HIP 95925 60138.2418 786.74 ± 0.26 29.48 ± 0.04 61.44 ± 0.03 120.06 ± 0.16 12.805 ± 0.008 90.58 ± 0.17
HIP 114382 60138.3045 823.06 ± 0.27 149.19 ± 0.04 64.36 ± 0.07 239.49 ± 0.16 12.788 ± 0.015 90.30 ± 0.07
HIP 116880 60138.4111 690.17 ± 0.23 195.24 ± 0.04 53.82 ± 0.04 285.76 ± 0.16 12.824 ± 0.010 90.52 ± 0.05
Weighted mean 12.805 ± 0.027 90.40 ± 0.08
ward option for HiRISE. Moreover, most astrometric fields are
too faint or too extended to be observed with the FIM tracking
camera.
During commissioning we observed a total of 8 binaries that
were recalibrated in separation and position angle using IRDIS,
and used to determine the pixel scale and North orientation of
the HiRISE tracking camera. IRDIS images are obtained in the
K band with K1 dual-band imaging filter of the K12 pair (Vigan
et al. 2010). They are corrected for the 1.0075 ± 0.0004 anamor-
phic distortion, and the position of the two components of each
binary is fitted with a 2d Gaussian. Based on these position, we
compute on-sky separation and position angle using the known
12.258±0.004 mas/pix pixel scale in K1 and −1.76◦
±0.04◦
true
North correction for IRDIS (Maire et al. 2021). FIM images are
obtained on the tracking camera using a series of 17 offsets with
the tip-tilt mirror to pave the field. Similarly to IRDIS images,
position of the two components of the binaries and determined
using a 2d Gaussian, and the detector separation and position
angle are computed. Finally, the pixel scale and true North cor-
rection are derived for each binary. All the commissioning values
are summarized in Table 2.
Like IRDIS, the FIM is affected by an anamorphic distor-
tion due to the SPHERE toric mirrors (Hugot et al. 2012) lo-
cated upstream in the optical path. We calibrate the amplitude
of the anamorphosis with the distortion grid of the SPHERE
calibration unit (Wildi et al. 2010) by comparing the distances
between all pairs of points along the horizontal and vertical di-
rections. With this method, we estimate a scale difference of a
factor 0.42% ± 0.10% between the horizontal and vertical direc-
tions. To correct for this effect, the FIM images must be extended
by a factor 1.0042 along the vertical direction.
We use a weighted mean to combine the pixel scale and
North correction values from Table 2. The weights used in the
combination are inversely proportional to size of the error bar for
each data point, to give less weight to the points with larger error
bars. We finally determine values of 12.805±0.027 mas/pixel for
the pixel scale and 90.40◦
± 0.08◦
for the true North correction.
These values will off course be consolidated and refined in the
future with new observations of binaries as part of the long term
calibration plan of HiRISE.
5.2. Stability
The FIM is particularly sensitive to changes in temperature in-
side the SPHERE enclosure because it is ∼80 cm high and made
of aluminum. During commissioning we studied the stability of
the fibers with respect to the detector of the tracking camera with
a dedicated test. In this test, every minute for several hours, the
0.06
0.04
0.02
0.00
0.02
0.04
0.06
Displacement
of
[
/D]
9.5 10.0 10.5 11.0 11.5 12.0
FIM bench temperature [°C]
1.0
0.8
0.6
0.4
0.2
0.0
0.2
0.4
0.6
0.8
1.0
Displacement
of
[pix]
x
y
Fig. 10. Stability of the feedback fibers crossing point I with the FIM
bench temperature. I is computed as the crossing point, on the tracking
camera detector, between the two lines going through the image of op-
posite feedback fibers.
PSF of the SPHERE internal source is centered on the centering
fiber using the optimization described in Sect. 4.1, then an im-
age of the PSF is acquired with the tracking camera to record its
position (using a 2d Gaussian), and finally another image with
the tracking fibers illuminated is also acquired to record their
position (using a 2d Gaussian). At each iteration of the data ac-
quisition, the bench temperature and timestamps are recorded.
The centering fiber is used instead of the science fiber because
the centering optimization is much faster on that fiber. The fibers
are all packed together in the bundle, so there is no reason to as-
sume the possibility of a differential motion between the science
and centering fibers.
The result of this test is presented in Fig. 10. Instead of show-
ing the displacement of all four feedback fibers on the detec-
tor with temperature, we use the crossing point I as a proxy.
I is simply computed as the crossing point between lines go-
ing through the image of opposite feedback fibers. There is an
almost perfect correlation with temperature in both the x and
y directions, with Pearson correlation coefficient of −0.933 and
0.996 respectively. The combined displacement of I on the de-
tector is of 0.79 pix/◦
C, or 0.25 (λ/D)/◦
C at λ = 1.6 µm.
We also analyze in Fig. 11 the variation of the distance be-
tween I and the PSF with temperature. Here the PSF is used as
a proxy for the centering fiber since at each iteration the PSF is
centered using an optimization. Ideally, we would hope that the
Article number, page 11 of 17
12. A&A proofs: manuscript no. hirise_first_light
9.5 10.0 10.5 11.0 11.5 12.0
FIM bench temperature [°C]
2.0
1.5
1.0
0.5
0.0
0.5
1.0
1.5
2.0
Variation
of
PSF-
distance
[pix]
x
y
Fig. 11. Stability of the distance between I and the PSF with tempera-
ture. In this test the PSF location is used as a proxy for the position of
the centering fiber because before each acquisition the PSF is centered
on the fiber using an optimization.
60 40 20 0 20 40 60
Aberration offset [nm rms]
0.86
0.88
0.90
0.92
0.94
0.96
0.98
1.00
1.02
Normalized
injected
flux
Focus
Astig
0
Astig
45
Coma
x
Coma
y
Trefoil
0
Trefoil
30
Sperical
Fig. 12. NCPA measured at the level of the science fiber using aber-
ration offsets applied as Zernike modes on the SPHERE deformable
mirror (see text for details). The analysis was limited to focus, astigma-
tisms, comas, trefoils, and spherical aberration.
distance would remain perfectly constant with temperature. The
data is much noisier, with a standard deviation of the residuals
of the order of 0.5 pixel (0.16 (λ/D)/◦
C at λ = 1.6 µm), which
is probably due to the intrinsic accuracy on the centering fiber.
The distance appears stable in y, with a slope of +0.02 pix/◦
C
(+0.01 (λ/D)/◦
C at λ = 1.6 µm), but it is not the case in x, with
a slope of −0.76 pix/◦
C (−0.24 (λ/D)/◦
C at λ = 1.6 µm).
These results indicate that the loop described in Sect. 4.3 is
not perfectly accurate to compensate for the decentering of the
PSF on the science fiber with temperature. For a more accurate
correction, the temperature variations will need to be taken into
account in the loop to remain within the centering specification
of 0.1 λ/D recommended by El Morsy et al. (2022). This will be
investigated in the future after further testing with the system.
5.3. Non-common path aberrations
Wavefront aberrations are well known to decrease the coupling
efficiency of the telescope’s PSF in single mode fibers (Jo-
vanovic et al. 2015; Otten et al. 2021). During HiRISE com-
missioning we estimated the amount of low-order non-common
path aberrations (NCPA) at the level of the science fiber by in-
troducing ramps of aberrations using the high-order deformable
mirror (HODM) of SPHERE and measuring the flux at the out-
put on the SV camera of CRIRES. Aberrations were introduced
using Zernike modes from Z3 to Z10 (focus, astigmatisms, co-
mas, trefoils, and spherical aberration) with ramps ranging from
-100 to +100 nm rms in 15 steps. At each step, an injection opti-
mization was done on the science fiber to ensure proper centering
and maximize coupling efficiency. The Zernike modes are pro-
jected on 900 of the 990 Karhunen-Loève modes that are used
by SAXO to filter spatial frequencies that cannot be applied to
the HODM. The modes are then introduced with an offset on the
WFS reference slopes. This is the same method used by Vigan
et al. (2019) for the compensation of the NCPA with the ZELDA
wavefront sensor.
The results of the analysis are presented in Fig. 12. In this
figure, we plot the normalized flux measured at the output of
the fiber as a function of the introduced aberration offset. The
curves are all normalized by a common factor, which is the av-
erage value for all curves at zero nanometers of aberration. In
theory, all curves should cross for a value of zero, but in prac-
tice the noise and small differences in the convergence of the
centering introduce some variations of the order of 0.4%. The
biggest variation is observed for the astigmatism at 0◦
, which is
∼2% below the other curves. We measure a total of 47 nm rms
of optical aberrations at the level of the science fiber. This value
is lower than the 70 nm rms reported in Sect. 3.1 but we include
fewer terms than in the Phasics measurement (although aberra-
tions higher than the first order were found to be negligible) and
some variations can be expected coming from the SPHERE in-
strument itself (see e.g., Vigan et al. 2022a).
Globally, our analysis shows that the response of the system
to static NCPA is relatively flat in the ±40 nm rms range, with
losses of the order of 2% or less. This means that the system
is close to an optimal setup in terms of aberrations and that im-
proving the wavefront by compensating the measured NCPA will
only provide a limited gain on the injection efficiency. Of course,
in a photon starving regime, any small gain is desirable, but this
has to be weighted against the stability of the NCPA and the time
required to perform the NCPA calibration. These aspects will be
further explored in the future.
5.4. AO guide fiber leakage
During the observation of very faint companions as part of com-
missioning, we discovered the existence of a leakage from the
AO guide fiber into the slit, almost at the location of the science
fiber. This is illustrated in Fig. 13 with the observation of a com-
panion that has a visual magnitude of H = 12.6, for two different
orders and science detectors.
The effect shows a strong variation with wavelength. In the
first spectral orders (Fig. 13, top), the pattern of the leakage sig-
nal is very broad with many spatial features varying in intensity.
The signal of the leakage term completely dominates over the
signal of the companion, which is strongly attenuated by telluric
absorption in this range of wavelengths. In orders closer to the
center of the H band (Fig. 13, bottom), the leakage signal is more
peaked but still presents faint features extending at the location
Article number, page 12 of 17
13. A. Vigan et al.: First light of VLT/HiRISE
1494.9 1495.0 1495.1
Wavelength [nm]
Pixels
Companion
1494.9 1495.0 1495.1
Wavelength [nm]
Background
1494.9 1495.0 1495.1
Wavelength [nm]
Difference
1611.9 1612.0 1612.1
Wavelength [nm]
Pixels
1611.9 1612.0 1612.1
Wavelength [nm]
1611.9 1612.0 1612.1
Wavelength [nm]
Fig. 13. Examples of the AO guide fiber leakage into the slit and its impact on the science data. Order #2, detector #3 at the top, and order #5,
detector #2 at the bottom. The color scale and normalization are the same for all images, and the bad pixels have not been corrected. In this
example, the companion has a visual magnitude of H = 12.6 and the images are the sum of two DITs of 600 s. The position of the companion’s
signal in the raw data is identified with a white arrow.
of the science fiber and beyond. The peak flux of the leakage
signal is of the order of 1.6–1.8 ADU/s in both orders, which is
at least 10 times higher than the signal of the companion.
The origin of the leakage appears relatively obvious when
looking at Fig. 7. In this figure, the diffraction pattern of the
AO guide fiber clearly extends in between the ref2 and science
fibers. Moreover, the cross-like pattern diffraction indicates that
the leakage is strongly amplified by the pupil mask installed on
the MACAO deformable mirror. Without this mask the leakage
term would certainly still be present, but probably at a much
lower level.
During commissioning, the effect of the leakage was attenu-
ated by acquiring sky backgrounds with the AO guide fiber illu-
minated. The subtraction of the background is efficient at remov-
ing the contribution of the leakage signal (Fig. 13, third column),
but this cannot remove the induced photon noise. This is visible
in the difference images in Fig. 13 where a trail of high noise
residuals can be identified at the location of the leakage signal’s
peak. The fact that this leakage term is static, because induced by
calibration source, could also open the possibility to model and
subtract it. But again, this approach will not remove the added
photon noise in the data, which will certainly become problem-
atic for companions with higher visual magnitudes.
Different mitigation strategies can be considered. Unfortu-
nately it is not feasible to use one of the reference fibers instead
of the science fiber because the reference fibers are located off-
axis, or to use one of the dummy fibers because they are not
connected to anything. The easiest mitigation strategy is to de-
crease the intensity of the calibration source that feeds the guide
fiber. In the current configuration, an attenuation filter of a factor
∼103
is used in combination with the H-band filter in front of
the SV camera, and the DIT of the SV camera is set at its min-
imum value of ∼80 ms. Decreasing the intensity of the source
would be compensated by decreasing the attenuation to ∼5×102
or zero (the two other available values) or by increasing the DIT.
However, this will have an impact on the target acquisition pro-
cedure described in Sect. 4.2 and some careful verification of
the updated procedure will be required. A more complex miti-
gation strategy would be to work in open loop for the duration
of individual DITs (typically 600 s), possibly closing the loop
in-between DITs to correct for any temporal or thermal drifts.
Another option would be to have a low-pass filter in the halogen
source to cut any light above 1.4 µm and guide on the SV camera
Article number, page 13 of 17
14. A&A proofs: manuscript no. hirise_first_light
1450 1500 1550 1600 1650 1700 1750
Wavelength [nm]
0.00
0.01
0.02
0.03
0.04
0.05
Transmission
95th percentile
Median
HIP 108085
Design [as-built]
Fig. 14. Transmission curve obtained in the H1567 setting on HIP 108085 during commissioning in median seeing (seeing of 0.7–0.8′′
, unknown
τ0) and clear sky conditions. The design data is based on Vigan et al. (2022b) with some updates. It corresponds to the as-built design for the final
system, i.e. based on actual transmission measurements for SPHERE, CRIRES, and most HiRISE optics. The complete transmission budget at a
few selected wavelengths is provided in Table 3.
Table 3. As-built transmission budget
Component 1500 nm 1600 nm 1700 nm Description
Sky 91% 96% 98% From ESO SkyCalc
Telescope 80% 80% 80% 3 reflective surfaces + dust on primary mirror
SPHERE CPI 55% 57% 46% SPHERE commissioning measurements
FIM 87% 88% 90% 2 reflective + 4 transmissive optics, as-built AR coatings
Strehl 83% 85% 86% Bright guide star (R = 3), median conditions, SPHERE NCPA
Pointing error 88% 89% 90% 8 mas pointing error (El Morsy et al. 2022)
Coupling efficiency 76% 76% 76% VLT pupil
Fiber transmission 96% 95% 94% Fiber absorption, as-built AR coatings
FEM 91% 92% 93% 1 reflective + 3 transmissive optics, as-built AR coatings
CRIRES 16% 19% 19% AIT laboratory measurements
Total 2.7% 3.7% 3.1%
Measured on sky 2.2% 3.3% 3.1% HIP 108085, 0.7–0.8′′
seeing, clear sky conditions
in J band. The most appropriate mitigation strategy will be in-
vestigated in the near future and will be implemented for future
observations.
5.5. Transmission
The final aspect of performance is the end-to-end transmission
of the system. As highlighted by several works in the past (e.g.,
Wang et al. 2017; Otten et al. 2021; Delorme et al. 2021), end-
to-end transmission is the main performance driver when com-
bining HCI and HDS.
Transmission measurements were obtained during the last
night of commissioning on the bright star HIP 108085 (V = 3.01,
H = 3.43) in clear sky conditions. The DIMM instrument was
not working on that night, but the seeing was estimated to be
of the order of 0.7–0.8′′
by the VLT/FORS instrument and by
the telescope guide probe. Unfortunately, there are no estima-
tions of the coherence time τ0 for that night. Conditions were
very stable during the six 20 second science exposures, followed
by equivalent background exposures. The target acquisition and
centering on the science fiber was performed using the proce-
dure described in Sect. 4.2, but stopped after the centering of the
star. The flux extracted for the star from the CRIRES data was
compared to a black body computed at the temperature of the
star (Teff ≃ 12 000 K) and normalized using the 2MASS H-band
filter zero point and the H magnitude of the star. The result of
this analysis is presented in Fig. 14.
We measure a peak transmission for HiRISE of 3.9%, esti-
mated using the 95th
percentile of all the values3
, and a median
value of 2.7%. These values are perfectly compatible with the ex-
pectations from design based on transmission measurements for
SPHERE, CRIRES, and HiRISE optics and fibers (Vigan et al.
2022b). A breakdown of the transmission budget is provided in
Table 3 and the reader can refer to Vigan et al. (2022b) for more
specific details on the transmission budget.
5.6. First astrophysical results
To confirm the capability of HiRISE to correctly target and char-
acterize sub-stellar companions, we observed the brown dwarf
HD 984 B during the same night as HIP 108085. HD 984 is a
young (30–200 Myr) F7 star hosting a brown dwarf (Meshkat
3
The 95th
percentile is used to avoid the bias induced by telluric ab-
sorption in the sprectrum, which is not corrected in these observations.
Article number, page 14 of 17
15. A. Vigan et al.: First light of VLT/HiRISE
et al. 2015) with an estimated mass of 61±4 MJup (Franson et al.
2022). This system was selected based on the brightness of its
host star (H = 6.2), the moderate contrast of the companion
(∆H = 6.4 mag), and its angular separation of 190 mas that falls
well under the prospect of HiRISE (Vigan et al. 2022a).
We acquired six exposures on HD 984 B with a DIT of 600 s
each in the H1567 spectral setting. Additionally, we also ac-
quired one exposure of 60 s on the host star and two background
exposures of 600 s. The data are reduced using a custom-built
pipeline where the background and bad pixels are removed, the
companion flux is extracted, and the noise of each pixel is mea-
sured. For the wavelength calibration we use the official CRIRES
pipeline recipe (Dorn et al. 2023), without any additional correc-
tion. This custom-built pipeline will be explained in more details
in forthcoming publications.
As a preliminary analysis, we simply confirm the detection
of HD 984 B using a modified cross-correlation function (CCF;
Ruffio et al. 2019; Wang et al. 2021b). In short, we estimate
the maximum likelihood value for both the companion and the
stellar signal, extracted from the HiRISE data, as a function of
RV shift for a given BT-Settl template atmospheric model at the
Teff expected for the companion (∼2 700 K, Johnson-Groh et al.
2017). In this analysis we use all the orders across the three
CRIRES detectors, covering a wavelength range from 1.43 to
1.78 µm.
Figure 15 presents the results of this modified cross-
correlation for the companion and the star. Both CCFs are nor-
malized by their respective standard deviations computed for RV
values outside the ±150 km s−1
range. We confirm the clear de-
tection of HD 984 B at an SNR of ∼15 and with an RV shift of
−28 km s−1
, taking into account the radial velocity of the host
star and the barycentric corrections. This is in good agreement
with the shift expected from orbital predictions based on previ-
ous observations (Meshkat et al. 2015; Johnson-Groh et al. 2017;
Costes et al. in prep.), which is estimated to −31 km s−1
using the
tool whereistheplanet (Wang et al. 2021a).
The CCF of the companion appears broadened with respect
to the auto-correlation function of the atmospheric template, in-
dicative of a significant rotational broadening. We estimate a ro-
tational velocity of v sin i ∼13 km s−1
, which is consistent with
the rotational velocity measured on K-band KPIC data (Costes
et al., in prep.).
6. Conclusions & prospects
The HiRISE instrument for the VLT builds on two flagship in-
struments: the SPHERE exoplanet imager and the CRIRES high-
resolution spectrograph. The goal of this new instrument is the
detailed spectral characterization of young EGPs in the H band
to better understand their formation, composition, and evolution.
The system has been implemented in a challenging environ-
ment, with the major constraint of not impacting the regular op-
erations of SPHERE, CRIRES, or the telescope. In SPHERE, the
FIM has been installed in the NIR arm of the IFS to benefit from
the space available there. It includes a tip-tilt mirror to move the
image with respect to the science fibers and a tracking camera
for monitoring and target acquisition. The FIM is complemented
with a dedicated electronics cabinet that contains the instrument
workstation, the calibration sources, and the control electronics.
Then, an 80 meters long fiber bundle is used to link SPHERE
and CRIRES around the UT3. The bundle includes fibers dedi-
cated to science and fibers dedicated to calibrations. All but one
fiber are based on the Nufern 1310M-HP telecom fiber, made of
fused silica, which offers extremely high transmission in the H
100 50 0 50 100
RV [km/s]
5
0
5
10
15
SNR
HD 984 B
Star
Auto-correlation
Fig. 15. Detection of the sub-stellar companion HD 984 B using 60 min
of HiRISE commissioning data. The plot shows the normalized CCF
between the HiRISE data on the companion and a BT-Settl model at
2 800 K in blue, the CCF between the stellar signal and the same model
in gray, and the auto-correlation function of the model in black (see
Sect. 5.6 for details). We measure a radial velocity of −28 km s−1
(red
dashed line) and a projected rotational velocity v sin i ∼13 kms.
band. Finally, the FEM is a simpler module installed in the cal-
ibration carrier stage at the entrance of CRIRES. It is designed
to reimage the output of the fiber bundle at the entrance of the
instrument with the focal ratio of the VLT.
We have developed an operational model that is a mix be-
tween existing observing VLT software templates, some new
dedicated templates, and some python procedures. These tools
are combined to perform calibrations that are necessary to accu-
rately center the stars’ or companions’ PSFs on the science fiber,
and to maintain this centering over the course of long exposures.
One of the operational challenges is related to the MACAO adap-
tive optics system in CRIRES that requires a dedicated guide
fiber to work in closed-loop and maintain a perfectly flat and
stable deformable mirror. The second main challenge is related
to the accurate centering of the PSF on the science fiber. For
this particular issue we have opted for a procedure that is fully
done on the internal calibration source of SPHERE and relies on
the DTTS to place the PSF at exactly the same location when
switching to the actual star. This procedure has been found to be
extremely reliable, but more investigations are required.
Different aspects of calibration and performance have been
investigated. In particular, we have found that the instrument is
not stable with variations of temperature, which implies that the
PSF will move in front of the science fiber when the temperature
varies. The FIM includes a feedback channel that allows imag-
ing calibration fibers on top of the science image on the tracking
camera. We have found that there is a good correlation between
the motion of these spots with the image of the science fiber,
but there is still a small differential motion that will need to be
compensated in the future. This will enable optimizing the per-
formance during nights where there are significant variations of
temperature.
We also measured a total of ∼50 nm rms of optical aberra-
tions at the level of the science fiber. These NCPA could be com-
pensated in the future, depending on stability, but our measure-
ments show that the gain to be expected is only marginal.
We identified a small leakage signal originating from the
AO guide fiber. Currently, the level of this signal is significantly
Article number, page 15 of 17
16. A&A proofs: manuscript no. hirise_first_light
higher than the signal of sub-stellar companions in long expo-
sures. This effect seems to be amplified by the presence of a
pupil mask on the deformable mirror of MACAO, which creates
diffraction spikes at a location just beneath the science fiber. We
will investigate the possibility to decrease the intensity of the
calibration source that feeds the fiber or to work in open loop
during science exposures.
Finally, we obtained a first estimation of the end-to-end
transmission of the system, which is a driving parameter of the
final performance. With a peak transmission of 3.9%, and a me-
dian transmission of 2.7%, we are almost exactly at the level ex-
pected from the design using actual measurements of SPHERE,
CRIRES, and most as-built HiRISE optics. We also presented
our first clear astrophysical detection of the brown dwarf com-
panion around HD 984. These results are extremely encouraging
for the execution of an ambitious science program for the under-
standing of EGPs with HiRISE in the coming years (Otten et al.
2021).
HiRISE on the VLT, like KPIC on Keck and REACH on
Subaru, are pathfinder instruments for the future of very high
contrast imaging science, either on the current telescope (e.g.,
RISTRETTO on the VLT, Lovis et al. 2017) or on future ex-
tremely large telescopes (e.g., PCS on the ELT, Kasper et al.
2021). They constitute stepping stones for ground-based instru-
ments that may, one day, enable the detection of telluric planets
around nearby stars.
Acknowledgements. The HiRISE team is extremely grateful to ESO and the
Paranal observatory staff for their major support throughout the whole project,
and especially during the installation and commissioning phase in June/July
2023. Thank you so much everyone! This project has received funding from the
European Research Council (ERC) under the European Union’s Horizon 2020
research and innovation programme, grant agreements No. 757561 (HiRISE) and
678777 (ICARUS), from the Commission Spécialisée Astronomie-Astrophysique
(CSAA) of CNRS/INSU, and from the Action Spécifique Haute Résolution
Angulaire (ASHRA) of CNRS/INSU co-funded by CNES, and from Région
Provence-Alpes-Côte d’Azur under grant agreement 2014-0276 (ASOREX).
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1
Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
e-mail: arthur.vigan@lam.fr
2
Institute for Astrophysics, Georg-August University, Friedrich-
Hund-Platz 1, 37077 Göttingen, Germany
3
European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2,
85748 Garching, Germany
4
Center for Advanced Instrumentation, Durham University, Durham,
DH1 3LE, United Kindgom
Article number, page 16 of 17
17. A. Vigan et al.: First light of VLT/HiRISE
5
European Southern Observatory, Alonso de Cordova 3107, Vitacura,
Santiago, Chile
6
Physics & Astronomy Dpt, University of Exeter, Exeter, EX4 4QL,
UK
7
Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS,
Laboratoire Lagrange, France
8
Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France
9
INAF – Osservatorio Astronomico di Padova, Vicolo
dell’Osservatorio 5, 35122 Padova, Italy
10
Academia Sinica, Institute of Astronomy and Astrophysics, 11F
Astronomy-Mathematics Building, NTU/AS campus, No. 1, Section
4, Roosevelt Rd., Taipei 10617, Taiwan
11
Dept. of Astrophysics, University of Oxford, Keble Road, Oxford,
OX1 3RH, UK
12
Optical and Electronic Systems Department, Kazan National Re-
search Technical University
13
Institute for Astronomy, University of Hawaii at Manoa, Honolulu,
HI 96822, USA
14
École Normale Supérieure, Lyon, CRAL (UMR CNRS 5574), Uni-
versité de Lyon, France
15
Space Telescope Science Institute, 3700 San Martin Drive, Balti-
more, MD 21218, USA
Article number, page 17 of 17