Soft X-ray Telescope

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ASTROSAT A Multi-Wavelength Satellite 1st
Dedicated Indian Astronomical Mission
ISRO Satellite Centre (ISAC), Bangalore Tata
Institute of Fundamental Research,
Mumbai University of Leicester 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
X-RAY
UV/Opt
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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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UVIT Two Telescopes

• f/12 RC Optics
• Focal Length 4756mm
• Diameter 38 cm
• Simultaneous Wide Angle ( 28) images in FUV
  (130-180 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 ( lt 5 ms,
  small window )
• Gratings for Slit-less spectroscopy in FUV
  NUV
• R 100

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UVIT filters
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GALEX UVIT FoV (Circular dia)
1.24 degrees 27 arc-min No. of bands
2 (NUV, FUV) 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 lt
10 mag lt 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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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 (_at_ 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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LAXPC Effective Area
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Large Area X-ray Proportional Counter (LAXPC)
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LAXPC Collimator
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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 _at_ 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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CZT-Imager with a coded mask
(Qualification Model)
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CZT Detector 4 cm X 4 cm
HV Connector
Connectors
CZT crystal
Thermal conductor
Thermal conductor
ASIC
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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 (1 cps/mCrab)
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Soft X-ray Telescope
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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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SXT Engineering and Flight Models
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Astrosat SXT FM FPCA in Thermal Vacuum Chamber at
Birmingham University
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X-ray Reflectivity
Smoothness of 8 10 Angstroms
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• CCD Performance Nominal
• Noise 6 10 e-
• Resolution at Mn 157 eV (Lab Electronics)

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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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Door and Corner X-ray Calibration Sources
Optical LED Image
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SXT Effective Area vs. Energy (after subtraction
of shadowing effects due to holding structure)
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SXT Half Power Diameter for a point source at 1
keV
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Galactic centre with SXT
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Scanning Sky Monitor (SSM)

• Detector 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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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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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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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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ASTROSAT Key Projects

• Supernova Remnants X-ray and UV Observations
• UVIT observations of
• Star Forming galaxies,
• Young stellar objects,
• Galactic Structure,
• Proto- and Planetary Nebulae
• UV Extinction in the Galaxy (Archival Data)
• Miscellaneous
• Study nano quasars and Compton thick sources,
• Observations of Stellar Flares,
• GLAST/INTEGRAL/BAT Sources,
• Surveys - multi wave, deep fields

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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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Large X-ray bandwidth and hard X-ray sensitivity
with low background Clusters of galaxies

• Science Drivers
• Measure temperature/abundance out to the
  virial radius and thus measure their total mass
• Measure the hard X-ray (non-thermal) emission
  component its relation with the motions of
  central bright galaxies, and large scale magnetic
  field

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SXT Clusters of galaxies
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Studying C-thin and C-thick AGN CXB
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NH in cm-2 1. 1023 2. 3x1023 3. 3x1024 4. gt1025
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4
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Binary X-ray Pulsars with Astrosat
Simulated 10 ks observations of hard X-ray
spectrum of Accreting Pulsar 4U 011563 The
cyclotron lines are well resolved by ASTROSAT
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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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Coming Next Year !
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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.