Indian Astronomy Satellite Mission (ASTROSAT)

National Institutions

1. ISRO, Bangalore

2. TIFR, Mumbai

3. IIA, Bangalore

4. RRI, Bangalore

5. PRL, Ahmedabad

International Institutions

1. University of Leicester, UK

2. Canadian Space Research Centre, Canada

Kallol MukerjeeDepartment of Astronomy and Astrophysics

Tata Institute of Fundamental Research (TIFR), Mumbai, INDIA

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 <10 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

ASTROSAT Instrument Configuration

Soft X-ray Telescope Soft X-ray Telescope (SXT)(SXT)

Cadmium Zinc Telluride Imager Cadmium Zinc Telluride Imager (CZT)(CZT)

Large Area X-ray Proportional Counter Large Area X-ray Proportional Counter (LAXPC)(LAXPC)

Scanning X-ray Sky monitor Scanning X-ray Sky monitor (SSM)(SSM)

UV Imaging Telescope (UVIT)(UVIT)

Soft X-ray Telescope (SXT)

CCD-22 based Focal Plane Camera

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 @ 1.5 keV

20 cm2 @ 6.5 keV

Sensitivity 10µ Crab (5 ; 10 4 s)

Position Accuracy 30 arcsecs

Large Area X-ray Proportional Counter (LAXPC)

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 < 20 keV)

~ 50 % in 20-100 keV

Time resolution 10 ms (10µ sec for event mode)

Sensitivity 14000 counts per sec per Crab Unit

CZT Imager Assembly

Radiator Plate

X connector

CAM with Holder

Collimator

CZT Top Housing

CZT Bottom Housing

Mounting/Interface Lug

Heat Pipe

Radiator Holding Bracket

Alpha Box

CZT CharacteristicsArea 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) > 100 keV

6o X 6o (10 – 100 keV)

Angular resolution 8’ (21’ geometric)

Energy resolution 5% @ 60 keV

Energy range 10 – 100 keV

Up to 1 MeV (Photometric)

Sensitivity 0.5 mCrab (5 ; 10 4 s)

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.

Principal Science Objectives of Astrosat

X-ray instruments1. Timing studies of X-ray Binaries

2. 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.

3. 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.

Principal Science Objectives of Astrosat X-ray instruments (continued…)

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?

Pulsar studies Spin up/down phases of pulsars.

Ultraviolet Imaging Telescope (UVIT)

Two Telescopes each of 38 cm Aperture (Twin Richey Chretian 2 mirror system)Three channels simultaneouslyFar 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 (>50 times that of HST)

Angular resolution = 1.8 arcsec (2-3 times better than GALEX) Time resolution = 1 s

Scientific Objectives with UVIT Deep Surveys: UV sky survey, Detection of galaxies at z ~ 2, Faint quasars and AGNs.

Lyman- 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

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