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Radio astronomy with SPIDER radio telescopes
FILIPPO BRADASCHIA Ph.D.
CEO and Co-founder
www.radio2space.com

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1) Introduction: discovery of the invisible Universe
2) How radio waves are generated in the Universe
3) How the Universe appears in radio waves
4) Radio2Space radio telescopes for radio astronomy
www.radio2space.com
Radio astronomy with SPIDER radio telescopes

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When we usually think about astronomy, we think of the stars at
night we can see from non-light polluted skies with the naked eye...
(image credit: Maurizio Casula)
Discovery of the invisible UniverseRadioastronomywithSPIDERradiotelescopes

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...or we think of the night sky we can observe and
photograph with our telescope.
BUTTHIS IS ONLY PART OFTHE STORY!
Discovery of the invisible UniverseRadioastronomywithSPIDERradiotelescopes

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Karl Jansky
(image credit: NRAO/AUI/NSF)
In 1931, studying strange interference in telephone
communications, Karl Jansky discovered radio waves
coming from the sky, eventually discovering their source as
the center of the Milky Way.
Discovery of the invisible UniverseRadioastronomywithSPIDERradiotelescopes

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Grote Reber with his radio telescope
(image credit: NRAO/AUI/NSF)
Fascinated by Jansky’s results, a young American engineer named
Grote Reber decided to build what we now consider to be the
first parabolic radio telescope (close to 10 meter diameter) with
an alt-azimuth mount in the garden of his home and built a
custom radio receiver.
Discovery of the invisible UniverseRadioastronomywithSPIDERradiotelescopes

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Grote Reber radio maps
(image credit: NRAO/AUI)
After his initial failures, in 1938, Reber began recording the radio
signals coming from the Milky Way. He also succeeded where
Jansky had failed - to attract the attention of astronomers by
converting the pure numerical data into maps of the radio sky,
like the one we can see here.
Discovery of the invisible UniverseRadioastronomywithSPIDERradiotelescopes

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The electromagnetic spectrum
Karl Jansky and Grote Reber discovered that objects in the
Universe emit not only the part of the electromagnetic spectrum
that we call light, but also also other types of electromagnetic
waves like radio (they also emit gamma rays, ultraviolet and
infrared) - and almost all of these electromagnetic waves can not
be perceived by our eye.
How radio waves are generated in the UniverseRadioastronomywithSPIDERradiotelescopes

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In fact from the ground we can’t detect all the electromagnetic waves because the Earth’s atmosphere blocks all of
the frequencies of the electromagnetic spectrum, except for visible light and radio waves. That's why astronomers,
if they wanted to explore particular frequencies, would have to use space telescopes - only an optical telescope or
a radio telescope can be used from the ground.
How radio waves are generated in the UniverseRadioastronomywithSPIDERradiotelescopes

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Natural emission of electromagnetic waves
Across the entire electromagnetic spectrum, objects emit waves for many different reasons but it’s important to know that
they are divided into 2 main classes: THERMAL RADIATION has an intensity that increases with the frequency and NON-
THERMAL RADIATION with an intensity that decreases with increasing frequency. This division is fundamental because,
even considering only radio waves, there are some objects that emit high frequency waves (and they are calledTHERMAL
SOURCES) while others are emit low frequency waves (they are called NON-THERMAL SOURCES).
How radio waves are generated in the UniverseRadioastronomywithSPIDERradiotelescopes

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Thermal emission: Wien’s displacement law
Thermal emissions are regulated by a fundamental law called
“Wien's displacement law”.
In practice, this law states that the emitted radiation, with an
increase in body temperature, has a peak of emission towards
shorter wavelengths. Hence all the bodies with a certain
temperature emit all the wavelengths.
How radio waves are generated in the UniverseRadioastronomywithSPIDERradiotelescopes

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electron
electron
Electromagnetic
wave emission
Non thermal emission: free-free
Other mechanisms, called NON-THERMAL, generate radio
waves through mechanisms that do not depend on temperature.
An example is the FREE-FREE EMISSION in interstellar hydrogen
clouds in which the light coming from nearby stars tends to
ionize (to make electrically charged) gases. The interaction
between the electrons and the positive ions change the
trajectory of moving charges which, according to Maxwell's laws
on electromagnetism, emits electromagnetic radiation.
How radio waves are generated in the UniverseRadioastronomywithSPIDERradiotelescopes

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Non thermal emission: synchrotron emission
Electron trajectory in
magnetic field
electron
radio emission
Magnetic field
flux line
Another example is the SYNCHROTRON EMISSION which occurs when a charged particle enters a magnetic field which,
based on the laws of electromagnetism, is forced in spiral movements around the field lines.The particle is thus accelerated
and there is an emission of electromagnetic waves.
How radio waves are generated in the UniverseRadioastronomywithSPIDERradiotelescopes

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Image credit: NRAO/AUI
All stars emit radio waves but the signals can be weak so they are hard to detect.The
Sun is one of the strongest radio sources in the sky because it’s the closest star to us.
The visible light is produced by a layer of the Sun called PHOTOSPHERE, while radio
waves are generated in external areas such as the CHROMOSPHERE or the CORONA.
In this 1420 MHz radio map you can see some "brighter" areas related to sunspots and
to non-thermal emissions generated by the magnetic field lines in sunspots.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit: NRAO
The Moon has a thermal emission and this radio map has been
recorded at a higher frequency than the previous one of the Sun.
The radio emission coming from our natural satellite comes from
a deep layer about 10 wavelengths (so to 30 cm deep if we
analyze it at 11 GHz, that is about 3cm of wavelength). For this
reason, the area of the Moon that in visible wavelengths is black,
in radio waves it is not completely black: in fact in this deep layer
there is always a residual heat.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit: NRAO/AUI
Solar System planets also emit radio waves even if, moving away
from the Sun, they are more difficult to detect as they become
increasingly cold. But JUPITER, at low frequencies (around 22 MHz)
has a very strong radio emission (not thermal) that derives from
electrons moving along the lines of force of its magnetic field. These
electrons derive from Io, one of Jupiter's satellites. Its volcanic
eruptions carry into the space gases that are ionized by ultraviolet
solar radiation and form an ionized cloud along its orbital plane.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit: NASA
Radio telescopes allow us to
explore a very different universe
from what we see in visible
wavelengths. In fact some
objects appear in the radio
universe that aren’t in the visible
one and vice versa.You can see
here how our galaxy, the Milky
Way, changes its appearance
when studied in different
wavelengths.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit (center): Argelander-Institut für Astronomie
Image credit (below): C.G.T. Haslam et al., Max-Planck- Institut für Radioastronomie
Please pay attention to how this image of the
sky changes in visible light (top left), compared
to radio waves (in the middle and in the lower
right). It seems to show a completely different
universe, but these pictures are an expression
of the same universe that changes if analyzed
at different wavelengths.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit: DSS - Digitized Sky Survey
Let's look at an example in detail: Note the
small galaxy in the center of this photo. This
galaxy is located in a particular area of the
constellation of the Swan and seems to us
normal, although it appears very weak and small.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit: NRAO/AUI
If we change frequency and look at its radio
image (recorded with a radio telescope) we
discover that the galaxy emits a large amount
of radio waves from material expelled from its
nucleus.The two "lobes" are generated from
continuous emission of matter from a black
hole at the center of the galaxy.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Courtesy: NRAO/AUI
Image credit: NRAO/AUI and N.E. Kassim,
Naval Research Laboratory
The interstellar gas present on the plane of the
Milky Way prevents us from seeing details at the
center of our galaxy. But radio waves pass
undisturbed through these areas.This way we can
study the areas that are related to the presence of
a black hole.Above, we can see the magnification
of the object located at the center of the Milky
Way (known as the Sagittarius A) in which ionized
gas whirls around the black hole.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit: NRAO/AUI
In addition to interstellar gas,
what are the main radio sources
in the Universe? Cassiopeia A is
one of the strongest and is a
supernova remnant. It is very
difficult to record in the visible
spectrum since it is obscured by
interstellar gas - it’s easy to
detect in radio waves.
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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Image credit: NRAO/AUI
The Crab Nebula (also known as
M1) in radio waves is called
Taurus A. It looks similar to the
visible images (bottom right) but
in the radio one (left) you can
see in the center a bright spot.
It’s a pulsar, a neutron star (a
supernova remnant that created
the nebula) that rotates on its
axis at a very high speed emitting
radio waves from its "poles".
How the Universe appears in radio wavesRadioastronomywithSPIDERradiotelescopes

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The Very Large Array radio telescope,
New Mexico (USA)
Radio telescopes, used to study the Universe in radio
wavelengths, are different from the telescopes we are used to:
they do not have the same lenses or mirrors that are used in
optical telescopes and that amplify the light that our eye is
sensitive too.
RadioastronomywithSPIDERradiotelescopes Radio2Space radio telescopes for radio astronomy

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RadioastronomywithSPIDERradiotelescopes
In a normal optical telescope (a Newtonian model shown here) a
concave (parabolic) mirror converges light towards a focal point.
This is then laterally reflected by a flat mirror towards the
eyepiece or camera.
Radio2Space radio telescopes for radio astronomy

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RadioastronomywithSPIDERradiotelescopes
A radio telescope with a parabolic
antenna works in a similar way. Instead
of a mirror, whose aluminized surface
reflects visible wavelengths, here
metallic "mirrors" are used to reflect
radio waves and send them to the
preamplifier at the focal point.
The received signal is then transmitted
through a special cable to the receiver.
Radio2Space radio telescopes for radio astronomy

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Northern Cross radio telescope,
Medicina (Italy)
RadioastronomywithSPIDERradiotelescopes
It is worth noting that the antenna design
may vary in different radio radio
telescopes. In fact, parabolic antennas are
usually used for frequencies higher than 1
GHz, while for lower frequencies, other
types of antennas are frequently used
(dipoles, for example).
The Northern Cross radio telescope
(left) of Medicina near Bologna - Italy, uses
special parabolic cylinder antennas to
study the 408 MHz frequency....
Radio2Space radio telescopes for radio astronomy

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32 meters radio telescope,
Medicina (Italy)
RadioastronomywithSPIDERradiotelescopes
...while radio astronomers use the large
parabolic antenna to receive signals
(MedicinaVLBI antenna works from 1.4
up to 23 GHz.) In this photo you can also
see the large alt-azi mount that is usually
the preferred solution to move such a
large antenna.
Radio2Space radio telescopes for radio astronomy

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RadioastronomywithSPIDERradiotelescopes
Radio telescopes study signals that are
usually very weak compared to
background noise of the receiver system.
That’s why professional radio astronomers
use special receivers, complex computers,
and other radio devices to analyze the
radio signal kept.
Part of the "back-end" of the
Medicina radio telescope (Italy)
Radio2Space radio telescopes for radio astronomy

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SPIDER
RadioastronomywithSPIDERradiotelescopes
Radio astronomy is a fascinating science but can be difficult in execution.
That’s why we developed the SPIDER radio telescope - The first
compact radio telescope (available in different diameters) that brings
professional-level technology to the educational (schools, universities, science
museums) and research (science institutes, space agencies) markets at an
affordable price.
Radio2Space radio telescopes for radio astronomy

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Diameter: 2.3 meter
Mount: equatorial
Weatherproof: no
Diameter: 3.0 meter
Mount: alt-az
Weatherproof: yes
Diameter: 5.0 meter
Mount: alt-az
Weatherproof: yes
RadioastronomywithSPIDERradiotelescopes
SPIDER radio telescopes are turnkey systems
composed of the antenna, mount, pier, receiver and
software, ready to capture radio waves coming from
space.Antenna diameters range from 2.3 to 5 meters.
Professional radio telescopeAdvanced radio telescopeCompact radio telescope
Radio2Space radio telescopes for radio astronomy

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H142-One 1420 MHz radio astronomy receiver
Central frequency: 1420 MHz
50 MHz received instantaneous bandwidth
1024 channels spectrometer
14 bit analog to digital converter
RadioastronomywithSPIDERradiotelescopes
Every SPIDER radio
telescope comes with the
H142-One receiver, a 1420
MHz frequency receiver,
radiometer and
spectrometer with all-in-
one design, very high
sensitivity and stability.
Designed and
developed with the
collaboration of the
Bologna INAF
Institute of Radio
Astronomy.
Radio2Space radio telescopes for radio astronomy

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RadioUniversePRO control and processing software
RadioastronomywithSPIDERradiotelescopes
SPIDER radio telescope is
controlled by
RadioUniversePRO
software, the complete
control and processing suite
for Radio2Space radio
telescopes. It features many
features like RFI removal,
antenna alignment,
planetarium, calibration,
spectra, radiometry, radio
maps, and more.
Radio2Space radio telescopes for radio astronomy

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RadioastronomywithSPIDERradiotelescopes
SPIDER radio telescopes are installed
outside and remotely controlled from
the control room where the receiver
and computer are housed.
Radio2Space radio telescopes for radio astronomy

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Instruments
SPIDER radio telescope
(antenna, mount and pier)
Control room
(receiver and software)
RadioastronomywithSPIDERradiotelescopes
The control room is connected to the
outdoor antenna and mount with
proper power and data cables installed
in an underground conduit.
Radio2Space radio telescopes for radio astronomy

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Result example: radio maps
Milky Way
Taurus A (M1 in radio waves)
This radio map has been captured in
daytime and with cloudy conditions!
RadioastronomywithSPIDERradiotelescopes
RadioUniversePRO allows the radio telescope
operator to capture a radio map of a defined
area of the sky. Starting from the definition of a
coordinate matrix, the software moves the
antenna to detect the radiometric value for
every point, then generate the map.
Radio2Space radio telescopes for radio astronomy

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Result example: neutral Hydrogen line detection
Neutral Hydrogen line
recorded on the Milky Way plane
The neutral Hydrogen line has been
captured in daytime and with cloudy
conditions!
RadioastronomywithSPIDERradiotelescopes
Other results can be recorded by creating a
calibrated spectrum - After an automatic goto/
slew to a radio source, the software performs a
spectrum capture (ON point) and performs a
calibration on the background noise (OFF point).
Radio2Space radio telescopes for radio astronomy

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Result example: Cross-Scan
Transit and capture of the radio signal
coming from the Sun
RadioastronomywithSPIDERradiotelescopes
With a Cross-Scan, RadioUniversePRO is able to
detect the maximum radiometric emission of the
object studied, by moving the antenna to different
positions in the sky.
Radio2Space radio telescopes for radio astronomy

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Accessories: hardware
NSGen noise generator for absolute calibration
to allow RadioUniversePRO software to calculate the flux
in Jy of a radio source or sky area.
RadioastronomywithSPIDERradiotelescopes
All-sky camera for SPIDER radio telescopes
to remotely see the radio telescope and the full-sky
both in day and night time.
UltraSonic Wind Sensor for SPIDER radio telescopes
to read wind speed and automatically park the radio
telescope if the wind exceed safety speed.
Radio2Space radio telescopes for radio astronomy

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Accessories: software
Networking module for RadioUniversePRO
allows remote control via the Internet (capabilities based
on the license).
RadioastronomywithSPIDERradiotelescopes
Multimedia module for RadioUniversePRO
allows RadioUniversePRO to be used in museums
and in more-general didactic use.
SETI module for RadioUniversePRO
extends the use of RadioUniversePRO to detect
possible artificial signals for SETI.
Radio2Space radio telescopes for radio astronomy

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Instruments
Installations:
New Mexico Tech college
near The Very Large Array (USA)
RadioastronomywithSPIDERradiotelescopes Radio2Space radio telescopes for radio astronomy

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Instruments
Installazioni: VLA
Installations:
Queens College (Hong Kong)
RadioastronomywithSPIDERradiotelescopes Radio2Space radio telescopes for radio astronomy

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Instruments
Installations:
Dr. Karl Remeis Observatory
in Deggendorf (Germany)
RadioastronomywithSPIDERradiotelescopes Radio2Space radio telescopes for radio astronomy

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Instruments
Installations:
Deggendorf Institute of Technology
(Germany)
RadioastronomywithSPIDERradiotelescopes Radio2Space radio telescopes for radio astronomy

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Instruments
Installations:
Visitor Center of Medicina radio
telescopes (Italy)
RadioastronomywithSPIDERradiotelescopes Radio2Space radio telescopes for radio astronomy

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Thanks to the Radio2Space radio telescopes,
you don’t need to be a radio astronomer to perform real radio astronomy!
RadioastronomywithSPIDERradiotelescopes Radio2Space radio telescopes for radio astronomy