Indian%20Astronomy%20Satellite%20Mission%20(ASTROSAT)

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Indian Astronomy Satellite Mission (ASTROSAT)
Kallol
Mukerjee Department of Astronomy and
Astrophysics Tata Institute of Fundamental
Research (TIFR), Mumbai, INDIA

• National Institutions
• ISRO, Bangalore
• TIFR, Mumbai
• IIA, Bangalore
• RRI, Bangalore
• PRL, Ahmedabad

• International Institutions
• University of Leicester, UK
• 2. Canadian Space Research Centre, Canada

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ASTROSAT

• The first fully dedicated multi-wavelength
  Indian astronomy mission
• To be launched from India in 2008 using PSLV
  at 600 km near
• equator at low inclination angle lt10 degrees
• Cover wide X-ray energy band 0.3-100 keV along
  with UV and
• Optical wave bands
• Timing, Spectroscopy, Imaging and long term
  monitoring
• Every instrument is configured in its own
  inherent features to
• achieve scientific requirements in specified
  wave band
• ASTROSAT is conceived with the prime objective
  is to do front
• ranking research utilising multi-wave length
  capabilities

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ASTROSAT Instrument Configuration
Large Area X-ray Proportional Counter (LAXPC)
UV Imaging Telescope (UVIT)
Soft X-ray Telescope (SXT)
Scanning X-ray Sky monitor (SSM)
Cadmium Zinc Telluride Imager (CZT)
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Soft X-ray Telescope (SXT)
CCD-22 based Focal Plane Camera
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SXT Characteristics
Telescope Focal Length 2.0 metres
Telescope Mirrors Conical shells
Telescope PSF 3 - 4 arcmin
Field of view 41.3 x 41.3 arcmin
Detector MAT CCD-22 (cooled to -80 deg C)
Detector Format 600 x 600 pixels
Pixel Scale 4.13 arcsec/pixel
Detector Readout Modes Photon counting, Imaging Timing
Energy Range 0.3 8.0 keV
Effective Area 200 cm2 _at_ 1.5 keV 20 cm2 _at_ 6.5 keV
Sensitivity 10µ Crab (5 ? 10 4 s)
Position Accuracy 30 arcsecs
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Large Area X-ray Proportional Counter (LAXPC)
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LAXPC Characteristics
Collimator field of view 1 0 x 10 for all the LAXPCs
Collimator height 45 cm for FOV collimator
Material for the Collimator 50µ Sn 25µ Cu 100µ Al
Absorber Gas 90 Xenon 10 Methane
Gas Pressure Two atmosphere (1670 torr)
Detector Window 50 (or 25) µ thick Mylar coated one side with 500 Å thick Aluminium
Energy range 3-80 keV
Average detection efficiency 100 (E lt 20 keV) 50 in 20-100 keV
Time resolution 10 ms (10µ sec for event mode)
Sensitivity 14000 counts per sec per Crab Unit
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CZT Imager Assembly

Radiator Holding Bracket

• Radiator Plate

Heat Pipe
X connector
CAM with Holder
Collimator
Alpha Box
Mounting/Interface Lug
CZT Top Housing
CZT Bottom Housing
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CZT Characteristics
Area 1024 cm 2
Pixels 16384
Pixel size 2.5 mm X 2.5 mm (5 mm thick)
Read-out ASIC based (128 chips of 128 channels)
Imaging method Coded Aperture Mask (CAM)
Field of View 17o X 17o (CAM) gt 100 keV 6o X 6o (10 100 keV)
Angular resolution 8 (21 geometric)
Energy resolution 5 _at_ 60 keV
Energy range 10 100 keV Up to 1 MeV (Photometric)
Sensitivity 0.5 mCrab (5 ? 10 4 s)
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Principal Science Objectives of Astrosat X-ray
instruments
1. Timing studies of X-ray Binaries

• Measure periodicities and their evolution
  including Pulsations, QPOs, Binary periods etc.
  (Studies of QPOs above 20 keV is relatively
  unexplored field).
• Timing and spectral evolution of X-ray bursts,
  flares and other sporadic variability.
• Studies of X-ray Transients and their temporal
  and Spectral characteristics.
• Long and Short term variability in AGNs.

1. Studies of continuum X-ray emission over a broad
   band of 3-80 keV.

X-ray Binaries, Supernova remnants
(SNRs), CVs, Stellar Coronae, AGNs etc.
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Principal Science Objectives of Astrosat X-ray
instruments (continued)

1. Detection of non-thermal components in the X-ray
   spectra of SNRs and Clusters of Galaxies

By accurate spectral measurements in 3 80
keV band in combination with Simultaneous
measurements from SXT in 0.3 8 keV region to
understand the acceleration processes and
origin of cosmic rays in the case of SNRs.
4. Measuring magnetic fields of neutron stars
By detection and studies of cyclotron lines,
most of which lie in 10 60 keV region
in the spectra of X-ray
pulsars.
5. Correlated time variations of intensity

• In 3-80 keV band with those in the visible,
  UV and soft X-ray (0.3-8 keV) bands
• to investigate the origin and mechanism of
  emission of radiation in different wave
• bands.

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Scientific Objectives of SSM

• To detect and locate new transients
• Long period Be binaries, X-ray novae,
  etc.
• Alert observers
• Point Astrosat, carry out optical
  identification and obtain system parameters like
  
• mass function, binary period, mass of
  the compact object etc..
• Study X-ray binary sources over a large dynamic
  range
• L 1033 to 10 38 erg/s dM/dt.
• Source states
• Low hard state, High soft state,
  Intermediate, very high etc.
• Super orbital period in HMXBs
• Precession period of disc/neutron
  star
• Long term cycles and Irregular variations in
  LMXBs
• Mass transfer instabilities?

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Ultraviolet Imaging Telescope (UVIT)

• Two Telescopes each of 38 cm Aperture (Twin
  Richey Chretian 2 mirror system)
• Three channels simultaneously
• Far UV (130 nm 180 nm),
• Near UV (180 nm 300 nm) and
• visible (350 nm 600 nm)
• Photon counting CCD based UV and optical
  detectors
• Filters FUV 135 nm, CIV (155 nm), 165 nm
• NUV CIII (190.9 nm), 225 nm, CII (235 nm), O
  II (247 nm), 255 nm, 285 nm
• Sensitivity 21 mag (in 1000 seconds)
• Field of view 30 arcmins (gt50 times that
  of HST)
• Angular resolution 1.8 arcsec (2-3 times better
  than GALEX)
• Time resolution 1 s

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Scientific Objectives with UVIT

• Deep Surveys UV sky survey, Detection of
  galaxies at z 2, Faint quasars and AGNs.
• Lyman-a Surveys Nearby galaxies clusters of
  galaxies.
• Galaxies in UV Evolution of stellar populations,
  OB stars, Dust properties, morphology.
• Hot Stars in the local group of galaxies global
  studies of young population
• In the Milky Way
• Studies of populations of sub-classes of
  White Dwarfs, WDs in the globular clusters
• High Mass Stars and luminous blue variables
  distance calibrators
• Interstellar Matter Probes
• Stellar Solar Connection (cool stars
  Rotation, magnetic activity, UV flares)
• Cataclysmic Variables and X-ray Binaries

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ASTROSAT Key Scientific Objectives

1. SIMULTANEOUS COVERAGE (UV, Soft X-rays and Hard
   X-rays) Environment of BLACK-HOLES and other
   ACCRETION POWERED sources.
2. WIDE BAND X-ray SPECTROSCOPY Continuum line
   emission Separation of thermal and non-thermal
   components.
3. TIMING Pulsars, QPOs etc.
4. TRANSIENT SOURCES
5. UV SURVEY, Young stellar Populations