The Palomar Transient Factory (PTF) uses the 48-inch Samuel Oschin Telescope at Palomar Observatory to discover transients and variables in the sky. It aims to study extragalactic and galactic phenomena such as supernovae, tidal disruption events, cataclysmic variables, and structures in the Milky Way. The PTF uses a wide-field imager to discover objects and then coordinates follow-up with spectrographs on the Palomar 200-inch and other telescopes. It has discovered over 2,000 supernovae and published numerous science papers. The Zwicky Transient Facility (ZTF) will improve on the PTF with a larger field of view

1. Producing Science with the Palomar
Transient Factory
Branimir Sesar (MPIA, formerly Caltech)

2. Survey Goals
(Law et al. 2009, Rau et al. 2009)
• Goal: to study the transient and variable sky
• Extragalactic
• Transients in nearby galaxies, CC SNe, TDE, Hα Sky Survey,
search for eLIGO/EM counterparts
• Galactic
• AM CVn systems (H + He WD), CVs, RR Lyrae stars, Milky
Way structure and dynamics
• Solar System: KBOs, small asteroids (prospect for growth
→ asteroid retrieval mission)

3. P48 wide-field imager →
Discovery engine
P48 wide-field imager →
Discovery engine P200
Spec. followup
P200
Spec. followup
P60
Photo. followup
P60
Photo. followup

4. P48 wide-field imager →
Discovery engine
P48 wide-field imager →
Discovery engine
P200
Spec. followup
P200
Spec. followup
P60
Photo. followup
P60
Photo. followup
Fast spectroscopic typing
with SED Machine (R~100,
PI: Nick Konidaris, Caltech)
Fast spectroscopic typing
with SED Machine (R~100,
PI: Nick Konidaris, Caltech)
R~100 spectra of various transients and variables
→ important spectral features are still discernible
R~100 spectra of various transients and variables
→ important spectral features are still discernible

5. P48 Overview
• 7.26 deg2
field-of-view → will
be upgraded to 47 deg2
for
ZTF (2015-2016)
• 1” / pixel resolution → barely
sampled at median 2” seeing
→ PSF photometry possible
• Robotic telescope &
scheduler → automatic
selection of fields → time &
money saver
• g', R, and 2 Hα filters
• ~250 images / night
CFHT12k camera
(some cosmetics, ghosts)
CFHT12k camera
(some cosmetics, ghosts)

6. PTF Image
Differencing
Engine (PTFIDE;
Frank Masci,
IPAC)
PTF Image
Differencing
Engine (PTFIDE;
Frank Masci,
IPAC)
Real-time Pipeline (transients)

7. Real-time Pipeline (transients)
Time from exposure to alert: 20 – 40 minTime from exposure to alert: 20 – 40 min

8. IPAC Pipeline (variables & light curves)
• Repeatability of < 0.01 mag
• R-band 5σ limit @ 20.6 mag
(aperture), 20.9 mag (PSF)
• 12,000 deg2
with >30 epochs
• 1st
PTF/iPTF data release (M81, M44, M42, Cas A, Kepler)
http://www.ptf.caltech.edu/page/first_data_release
• Public release of PTF, iPTF and ZTF data (w/ NSF funding)
coverage of the Galactic plane (|b| < 5 deg)coverage of the Galactic plane (|b| < 5 deg)

9. Science
• 2,254 spectroscopically
confirmed SNe
• 88 publications (5 in
Nature)
SN Ia in M101 (PTF11kly;
Nugent et al. 2011, Li et al. 2011)
SN Ia in M101 (PTF11kly;
Nugent et al. 2011, Li et al. 2011)

10. An outburst from a massive star 40 days
before a supernova explosion (Ofek+ 2013)
No detection @ -60 daysNo detection @ -60 days
Outburst!Outburst!
Explosion!Explosion!

11. Localization of an optical afterglow in 71
deg2
(Singer et al. 2013)
ZTF will cover this area
with ~2 images
ZTF will cover this area
with ~2 images

12. GRB 130702A to iPTF13bxl Timeline
• 00:05 Fermi GMB trigger (UT July 2nd)
• 01:05 position refined by human (GBM group)
• 03:08 Sun sets at Palomar
• 04:17 PTF starts observations
• 04:17 PTF starts observations (10 fields, 2x60-s per field; 72 square degrees)
• 4214 "candidates": 44 were known asteroids, 1744 were coincident with stars (r<21) → 43
viable candidates
• Human inspection reduced this to 6 excellent candidates
• iPTF13bxh core of a bright galaxy, iPTF13bxr known quasar, iPTF13bxt was close to a
star in SDSS
• Remaining candidates: iPTFbxl(RB2=0.86), iPTFbxk (RB2=0.83) and iPTFbxj (RB2=0.49)
• Sunrise in California

13. GRB 130702A to iPTF13bxl Timeline
• 00:50 Swift observations for iPTF13bxl requested → X-ray
source detected
• 04:10 Robotic observations of these candidates at P60 →
iPTFbxl showed decline relative to first P48 observation (!)
• 04:24 Spectral observations on the Palomar 200-inch →
spectrum is featureless (!!)
• 08:24 Announced iPTF13bxl as afterglow (ATEL, GCN)
• 17:34 LAT localization (3.2 square degrees)
• 19:03 IPN announces annulus of width 0.9 degrees
• 23:17 Magellan observations led to z=0.145

14. Small, but potentially hazardous asteroids
Adam Waszczak
(grad student @
Caltech)
Adam Waszczak
(grad student @
Caltech)
NEA 2014 JG55 (diameter: 10 m, closest approach: ¼ Earth-Moon distance)NEA 2014 JG55 (diameter: 10 m, closest approach: ¼ Earth-Moon distance)

15. ~180 RRab stars between 60 and 100 kpc
Orange – Sgr?Orange – Sgr?

16. ΛCDM prediction: Hundreds of ultra-faint
dSph galaxies orbiting the MW
ultra-faint
dSph
ultra-faint
dSph
Tollerud et al. (2008)Tollerud et al. (2008)
Predicted number of observable
faint MW satellites
Predicted number of observable
faint MW satellites
• LSST should be able to
observe ~300 ultra-faint
dSphs
• About 50 ultra-faint dSphs
in ~10,000 sq. deg and
between 60 - 100 kpc

17. Segue I (MV
= -1.5, D = 23 kpc, rh
= 30 pc)
MSTOMSTO
RRcRRc
BHBBHB
Only 6
RGB stars!
Only 6
RGB stars!
Seg RGB → orange
Seg MS → blue
Seg RGB → orange
Seg MS → blue

18. “Segue I”-like ultra-faint dSph at 60 kpc
dSph RGB → orange
foreground → white
dSph RGB → orange
foreground → white

19. Segue I (MV
= -1.5, D = 23 kpc, rh
= 30 pc)
MSTOMSTO
RRcRRc
BHBBHB
Only 6
RGB stars!
Only 6
RGB stars!
Seg RGB → orange
Seg MS → blue
Seg RGB → orange
Seg MS → blue

20. RR Lyrae Stars
• Old, evolved stars (> 9 Gyr) →
trace old populations of stars
• Standard candles → identify
them → know their distance
(with ~6% uncertainty)
• Bright (V ~ 21 at 110 kpc)
• Variable stars (P ~ 0.6 day)
with distinct light curves ( ~1
mag amplitude) → easily
identifiable
• Repeated observations (~30 or
more) are needed
Light curve of an RR Lyrae type abLight curve of an RR Lyrae type ab

21. Table 4 of Boettcher, Willman et al. (2013)
Boo III 1 -2.0 (Sesar, submitted to ApJ)
Boo II 1? ? (within 1.5' of Boo II @ 33 kpc)
Boo III 1 -2.0 (Sesar, submitted to ApJ)
Boo II 1? ? (within 1.5' of Boo II @ 33 kpc)

22. “Segue I”-like ultra-faint dSph at 60 kpc
dSph RGB → orange
foreground → white
dSph RGB → orange
foreground → white

23. Pick a distant RR Lyrae star
D = 60 kpcD = 60 kpc

24. Select stars that may be at the distance of
the RR Lyrae star
M92 isochrone
at 60 kpc
M92 isochrone
at 60 kpc

25. Plot angular coordinates with respect to the
coordinates of the RR Lyrae star

26. Convert angular to projected distances

27. Repeat for a different RR Lyrae star (i.e.,
sightline) and add onto the same plot

28. Repeat for a different RR Lyrae star (i.e.,
sightline) and add onto the same plot

29. Overdensity of sources when fdSph
= 1.0 ...

30. ...when fdSph
= 0.2

31. … when f = 0 (i.e., just the background)

32. What is observed in SDSS

33. Sensitivity of the detection method
Black pixels: parameter
space where a detection
is possible
Black pixels: parameter
space where a detection
is possible

34. RR Lyrae stars in SDSS Stripe 82 (Sesar, Ivezić+ 2010)RR Lyrae stars in SDSS Stripe 82 (Sesar, Ivezić+ 2010)
“Smooth” inner halo ends at 30 kpc → only streams
and dSphs beyond 30 kpc?
“Smooth” inner halo ends at 30 kpc → only streams
and dSphs beyond 30 kpc?

35. Be Aware of the Contamination
• Sesar et al. (2007):
• Smaller number of epochs
in SDSS Stripe 82
• Could not properly
remove non-RR Lyrae
stars
• ~30% contamination in
our RR Lyrae sample
• Detection of false halo
substructures
PscPsc