ASTROSAT: A Multi-Wavelength Satellite
1st Dedicated Indian Astronomical Mission
ISRO Satellite Centre (ISAC), Bangalore
X-RAY
Tata Institute of Fundamental Research, Mumbai
University of Leicester
UV/Opt
Indian Institute of Astrophysics (IIA), Bangalore
Inter-University Centre for Astronomy & Astrophysics
(IUCAA), Pune.
Canadian Space Agency
Raman Research Institute, Bangalore
Vikram Sarabhai Space Centre, Trivandrum
G.C.Stewart
Berlin
4/8/2015
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ASTROSAT (1.55 tons  600 kms, nearly equatorial orbit by PSLV, 3 gyros and 2
star trackers for attitude control by reaction wheel system with a Magnetic torquer )
2 UV(+Opt ) Imaging Telescopes
3 Large Area Xenon
Proportional
Counters
Soft X-ray
Telescope
Radiator Plates
For SXT and
CZT
CZTI
Scanning Sky
Monitor
(SSM)
Folded Solar panels
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Berlin
4/8/2015
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UVIT: Two Telescopes





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
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
f/12 RC Optics
Focal Length: 4756mm
Diameter: 38 cm
Simultaneous Wide Angle (
~ 28’) images in FUV (130180 nm) in one and NUV
(180-300 nm) & VIS (320-530
nm) in the other
MCP based intensified
CMOS detectors
Spatial Resolution : 1.8”
Sensitivity in FUV: mag. 20
in 1000 s
Temporal Resolution ~ 30
ms, full frame ( < 5 ms, small
window )
Gratings for Slit-less
spectroscopy in FUV & NUV
R ~ 100
G.C.Stewart
Berlin
4/8/2015
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Berlin
4/8/2015
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UVIT: filters
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Berlin
4/8/2015
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GALEX
FoV (Circular dia)
No. of bands
1.24 degrees
2 (NUV, FUV)
UVIT
27 arc-min
2 channels (NUV, FUV) + Vis
Filters in NUV
NIL
5 filters
Filters in FUV
NIL
5 filters [multiple colour-colour diagrams]
Spectroscopy
Grism
Grating
Resolution
R ~ 100-120
R ~ 100
No. of grism/grating
1 per band
2 per band
Angular resolution
4.5-6.0 arcsec
1.8 arc-sec (FWHM)
Saturation
< 10 mag
< 8.0 mag (neutral density filter)
[can image fields with bright objects]
Time resolution
~ 10 milli-sec
~ 5.0 milli-sec (window mode)
~ 30 milli-sec full field
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Berlin
4/8/2015
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Large Area Xenon Proportional Counter
(LAXPC): Characteristics
Energy Range
:
3-80 keV
(50 m Mylar window, 2 atm. of 90 % Xenon + 10 % Methane)
Effective Area
:
6000 cm² (@ 20 keV)
Energy Resolution : ~10% FWHM at 22 keV
Field of View :
1° x 1° FWHM
(Collimator : 50µ Sn + 25µ Cu + 100µ Al )
Blocking shield on sides and bottom : 1mm Sn + 0.2 mm Cu
Timing Accuracy :
10 μsec in time tagged mode
(oven-controlled oscillator).
Onboard purifier for the xenon gas
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Berlin
4/8/2015
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LAXPC: Effective Area
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Berlin
4/8/2015
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Large Area X-ray Proportional Counter (LAXPC)
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Berlin
4/8/2015
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LAXPC: Collimator
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Berlin
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CZT Imager characteristics
Area
1024 cm 2
Pixels
16384
Pixel size
2.4 mm X 2.4 mm (5 mm thick)
Read-out
ASIC based (128 chips of 128 channels)
Imaging method
Coded Aperture Mask (CAM)
Field of View
17 X 17 deg2 (uncollimated)
6 X 6 (10 – 100 keV) – CAM
Angular resolution
8 arcmin
Energy resolution
5% @ 100 keV
Energy range
10 – 100 keV - Up to 1 MeV (Photometric)
Sensitivity
0.5 mCrab (5 sigma; 10 4 s)
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Berlin
4/8/2015
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CZT-Imager with a coded mask
(Qualification Model)
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Berlin
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CZT Detector
4 cm X 4 cm
Connectors
CZT
crystal
HV Connector
Thermal
conductor
Thermal
conductor
ASIC
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Berlin
4/8/2015
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SXT Characteristics
Telescope Length: 2465 mm (Telescope + camera + baffle + door)
Top Envelope Diameter: 386 mm
Focal Length:
2000 mm
Epoxy Replicated Gold Mirrors on Al substrates in conical
Approximation to Wolter I geometry.
Radius of mirrors: 65 - 130 mm; Reflector Length: 100 mm
Reflector thickness: 0.2 mm (Al) + Epoxy (~50 microns) + gold (1400
Angstroms)
Minimum reflector spacing: 0.5 mm
No. of reflectors: 320 (40 per quadrant)
Detector (Swift Heritage): E2V CCD-22 600 x 600
Field of view : 41.3 x 41.3 arcmin
PSF: 3 – 4 arcmins
Sensitivity (expected): few x 10-14 cgs
G.C.Stewart
(1 cps/mCrab)
Berlin
4/8/2015
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Soft X-ray Telescope
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Berlin
4/8/2015
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•Four Fe-55 calibration (corner) sources
•One Fe 55 calibration door source
•Optical Blocking Filter
•CCD Assy. including TEC
•PCB with front-end electronics
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Berlin
4/8/2015
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SXT Engineering
and Flight Models
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Berlin
4/8/2015
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Astrosat SXT FM FPCA in Thermal
Vacuum Chamber at Birmingham
University
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Berlin
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Berlin
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CCD Performance Nominal
• Noise ~6 – 10 e• Resolution at Mn ~157 eV (Lab Electronics)
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Berlin
4/8/2015
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SXT CCD (Eng.) Data with TIFR built Electronics
Isolated pixels only
5.9 and 6.4 keV peaks
Resolution ~140 eV
Si escape peaks
3.70 and 4.15 keV
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Berlin
4/8/2015
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Door and Corner X-ray Calibration
Sources
Optical LED Image
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Berlin
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SXT Effective Area vs. Energy
(after
subtraction of shadowing effects due to holding structure)
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Berlin
4/8/2015
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Scanning Sky Monitor (SSM)
 Detector
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



:
3 x Proportional counters
with resistive anodes
Ratio of signals on either ends of anode gives
position.
Energy Range :
2 - 10 keV
Position resolution :
1.5 mm
Field of View :
10o x 90o (FWHM)
Sensitivity
:
30 mCrab (5 min integration)
Time resolution
:
1 ms
Angular resolution :
~ 10 arc min
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Berlin
4/8/2015
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Status
 Engineering Environmental Tests almost complete
 Flight Model Construction Well Advanced (UVIT
detectors and SXT CCD camera complete)
 Spacecraft Assembly begun – most subsystems
complete
 Launcher Assigned
 Launch Date
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Berlin
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ASTROSAT – Key Strengths
 Simultaneous V/UV to hard X-ray measurements
 LEO+ 70 inclinclination Low , stable?
Background
 Large area at high X-ray energies
 UV imaging capability
 Low pile-up in CCD
 Fast Slewing ??
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Berlin
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ASTROSAT – Key Projects
1. AGN/Binaries: Simultaneous UV to hard X-ray
timing/monitoring
2. Galactic Novae: UV to X-ray Observations (TOO
program)
3. Magnetars: Multi-wave observations
4. LMXBs: Persistent Pulsations and thermonuclear
bursts
5. Galactic Black Holes and micro / nano quasars
6. Binary X-ray Pulsars: Cyclotron Resonance Scattering
Features (X-ray Observations)
7. Clusters of galaxies: X-ray & UV Observations
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Berlin
4/8/2015
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ASTROSAT – Key Projects
10. Supernova Remnants: X-ray and UV Observations
11. UVIT observations of
a)
b)
c)
d)
e)
Star Forming galaxies,
Young stellar objects,
Galactic Structure,
Proto- and Planetary Nebulae
UV Extinction in the Galaxy (Archival Data)
a)
b)
c)
d)
Study nano quasars and Compton thick sources,
Observations of Stellar Flares,
GLAST/INTEGRAL/BAT Sources,
Surveys - multi wave, deep fields
12. Miscellaneous:
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Berlin
4/8/2015
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AGN
(bright)
• 4/5 decade SEDs - Resolving all the spectral components : UV
and soft X-rays (thermal) from accretion disk, hard X-ray reflection
component, intrinsic power-law component
• Variability correlation and lags between UV, soft and hard X-rays
• Variability correlation and lags between Fe-K line and Compton
Reflection
•Bright Compton thick
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Berlin
4/8/2015
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SXT: Clusters of galaxies
LAXPC
H
C
SXT
CZTI
Spectral model from
Rephaeli et al. (1999)
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Berlin
4/8/2015
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Binary X-ray Pulsars with Astrosat
Simulated 10 ks observations of hard X-ray spectrum of Accreting Pulsar 4U
0115+63 The cyclotron lines are well resolved by ASTROSAT
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Berlin
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Time Allocation
PV Phase
(6
months)
Guaranteed
Time
(6 months
2nd Year
3rd Year
3+? Yr
X-ray Teams
67%
67%
32.5%
20%
_
UVIT Team
33%
33%
17.5%
10%
_
Indian
Proposals
_
_
35%
45%
65%
International
Proposals
_
_
_
10%
20%
Canada
_
_
5%
5%
5%
Leicester
_
_
3%
3%
3%
TOO
_
_
5%
5%
5%
Calibration
_
_
2%
2%
2%
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Berlin
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Coming Next Year !
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Berlin
4/8/2015
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Simultaneous UV to hard X-ray spectral
measurements with ASTROSAT: Blazars, HPQs,
OVVs etc.
Science Drivers: Jet Physics, particle injection and acceleration
• Synchrotron X-ray emission from the highest energy e• Electron/proton injection.
• Acceleration and cooling related variability patterns in Sync.
components of FSRQs and LBLs.
• UV and soft X-ray variability can pin down the transition
between the emission from slow and fast cooling e- and thus
obtain estimates of magnetic field and Doppler factors of the
jets.
• Shocks in jets. Geom: viewing angle, jet opening angle.
• Underlying Accretion disk in Blazars ? Can be revealed during
minima when the beamed component is suppressed.
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Berlin
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