AstroSat – Overview

S. Seetha

Programme Director Space Science Programme Office ISRO Headquarters, Bangalore

IUCAA 13th July 2016 AstroSat Science Goals Multiwavelength studies covering the energy bands of UV (NUV and FUV), limited optical, and X-ray regime (0.3 keV to 100keV) n High resolution (ms to microsec) timing studies- Continuous coverage – Periodic, aperiodic and chaotic variability; Evolution – Detection of new Accreting ms Binaries and AXPs. – Quasi periodic oscillations n Broadband spectral measurements – Continuum emission from all classes of UV and X-ray sources. – Thermal and non-thermal emission; – Detection and profiles of Cyclotron Features in spectra of X- ray Pulsars n High resolution imaging (~2 arc sec) in UV and moderate (few arcmin) imaging in soft X-rays – emission nebulae and supernova remnants – Hot stars in nearby galaxies; UV Morphology of galaxies

Spacecra and payloads

Large Area X-Ray Proporonal Ultra Violet Imaging Telescope Counter (LAXPC) (UVIT)

Cadmium Zinc Telluride Imager (CZTI)

So X-ray Telescope (SXT) Scanning Sky Monitor (SSM)

S/C in lted posion during pre-launch test at SHAR AstroSat - Mission objective

Design, develop, realize and launch a multi-wavelength astronomy satellite for studying the cosmic sources.

Launch: PSLV C-30 on 28 Sept. 2015 Orbit: 650 km, near-equatorial Inclination: ~ 6 degree S/C mass : ~ 1515 kg; Payload mass: ~855 kg Mission life : 5 years

• Altitude – 650km : to reduce effect of atomic oxygen • Inclination – 6 degree : to reduce effect of charge particle background due to South Atlantic anomaly or high latitude regions • Veto detector : to veto charge particle interactions • Bottom, sides S/C in axes defined configuration AstroSat payloads configuraon

Large Area X-Ray Proportional Counter Ultra Violet Imaging Telescope (LAXPC) Fast time variability; wide band (UVIT) NUV, FUV, Optical imaging; spectral coverage; 3-80 keV intensity variation (130-180 nm), ( 200-300 nm ), ( 320-550 nm )

Cadmium Zinc Telluride Imager (CZTI) Extend high energy range, good spectral Soft X-ray Telescope energy resolution if no (SXT) source confusion; solid Soft X-ray energy; state detectors (10-100 imaging in X-rays; keV) 0.3-8.0 keV

Scanning Sky Monitor (SSM ) Detect new X-ray transients, monitor known X-ray sources; 2.5 -10 keV AstroSat wavelength coverage CZTI

LAXPC SXT

UVIT

Photon energy (keV) 10-3 10-2 10-1 100 101 102 103

UV Hard X-rays

IR Visible So X-rays Gamma rays SSM 103 102 101 100 10-1 10-2 10-3

Wavelength (nm) Typical Electromagnec Spectrum First Indian satellite to be operated as an Observatory – Performance Verification (PV): First 6 months after launch; payloads will be switched ON in a sequence and their performance will be verified and calibrated; all the data belongs to payload teams. – Guaranteed Time (GT): 6 months period after PV phase completion; reserved for observations from the payload teams. – Regular observations: After completion of PV and GT; based on Announcement of Opportunity (AO) cycles; open to national and international user community – Target of Opportunity (ToO) aimed at new transient sources which cannot be predicted in advance – 2% of the observing time is reserved for calibration and for maintaining the health of the instruments

An announcement of opportunity (AO) is made in June 2016, for Indian researchers to submit proposals for observations with AstroSat for 35% of time. The observations for this AO cycle will be carried out during October

2016 – March 2017.

An AstroSat support Cell (ASC) has been established at IUCAA to train the proposers for proposal submission and data analysis. Mode of target selection

Proposal Pms + PVATAC & Mission submission Mission ATC operations in APPS

Geometrical Constraints Highlights of Operations

• Sun Avoidance Maneuver (SAM) n RAM angle (+ROLL and velocity vector) > 12˚ • Safe guarding P/L instruments from SAA n Terminator (+ROLL and Bright Earth • Attitude maintenance Limb) > 12˚ • Data availability to POCs- still n Sun Angle (+ROLL and SUN) > 65˚ continue to improve n Angle b/w +YAW and SUN > 90˚ • GS hardware, S/w and interfaces n Angle b/w Star Sensor and SUN > 50˚ Angle b/w +ROLL and Albedo > 12˚ To distant star

Earth pointing mode Inertial Pointing mode Source viewing Sun rays direction Eclipse or dark part of orbit

occult SAA

Not to Scale Flow of observation plan Proposers

Mission & SCC APPS ATAC Checking of all requirements Mission o/ps ATC P/l operations

Scheduler S/Ws Obs. seq gen Command seq gen ISSDC

Data reception AO proposers

Data products Level 0, 1,2 generation POCs at TIFR, ISAC,RRI,IIA Data Validation Archival and dissemination Other users after lock-in period Mission details

Payload Mass Power (kg) (W) Satellite mass 1515 kg

Instruments 855 kg UVIT 231.8 87.0 (Payloads) SXT 73.6 26.0 mass LAXPC 415.6 62.5 Spacecraft Cuboid shaped; 1.96 m x 1.75 m x 1.30 m CZTI 56.5 73.5 SSM 75.5 41.0 S/C Power 1626 W CPM 2.0 4.0 Launch PSLV C30 (XL) Vehicle Total 855.0 294.0 An Indian National Space Observatory A Collaborative Project of Different Centres of ISRO Tata Institute of Fundamental Research (TIFR), Mumbai Indian Institute of Astrophysics (IIA), Bangalore Inter-University Centre for Astronomy & Astrophysics (IUCAA), Pune. Raman Research Institute (RRI), Bangalore Physical Research Laboratory (Ahmedabad) Canadian Space Agency, Canada Leicester University, U.K.

With participation expected of Many Indian Universities and research centres