Highlights of the ASTROSAT Mission S. Seetha PI, ASTROSAT Programme Director Space Science Programme Office ISRO Headquarters Bangalore IACHEC, Pune 01 March 2016

India’s multiwavelength space astronomy mission is aimed at studying the celestial sources in X-ray ( keV), optical (320 – 550 nm), far UV (130 – 180 nm) and near UV (200 – 300nm) spectral bands simultaneously. Spacecraft and payloads are healthy. Payloads developed and operated by different centers of ISRO, TIFR, IIA, IUCAA, CSA, UoL, NCRA, PRL, RRI All the payloads are operational. Observations under progress. The preliminary results are made available in the ISRO website ( ASTROSAT Space astronomy observatory of India

Lift-off from SHAR at 10:00 hrs IST on 28 th Sep 2015 Thirtieth consecutive success for PSLV The spacecraft was launched successfully on 28th September 2015 from SDSC Sriharikota. Orbit: 650 km, near- equatorial; Inclination: ≤ 6 degree.

Ultra Violet Imaging Telescope (UVIT) Cadmium Zinc Telluride Imager (CZTI) Scanning Sky Monitor (SSM) Soft X-ray Telescope (SXT) Large Area X-Ray Proportional Counter (LAXPC) S/C in tilted position during pre-launch test at SHAR Spacecraft – actual view

Mission details Satellite mass1515 kg Instruments (Payloads) mass 855 kg SpacecraftCuboid shaped; 1.96 m x 1.75 m x 1.30 m S/C Power1626 W Launch Vehicle PSLV C30 (XL) PayloadMass (kg) Power (W) UVIT SXT LAXPC CZTI SSM CPM Total

ASTROSAT INSTRUMENTS Large Area X-ray Proportional Counter (LAXPC) Scanning Sky Monitor (SSM) UV Imaging Telescope (UVIT) Soft X-ray telescope (SXT) Cadmium Zinc Telluride Imager(CZTI)

Astrosat Science Goals Multiwavelength studies covering the energy bands of UV (NUV and FUV), limited optical, and Xray regime (0.3 keV to 100keV) 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 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 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 ;

Photon energy (keV) Wavelength (nm) Extreme UV Soft X-rays Hard X-rays Gamma rays IR Visible UV UVIT SXT LAXPC CZTI SSM Typical Electromagnetic Spectrum Broadband coverage in a single mission X-ray, Ultraviolet and limited optical

Large effective area in X-ray band Effective area of Large Area X-ray Proportional Counter (LAXPC) payload is  five times that of RXTE above 25 keV.

Highlights - Operations

S/C in axes defined configuration

Simultaneous multi-wavelength observations Large Area X-Ray Proportional Counter (LAXPC) Fast time variability; wide band spectral coverage Ultra Violet Imaging Telescope (UVIT) NUV, FUV, Optical imaging; intensity variation Cadmium Zinc Telluride Imager (CZTI) Extend high energy range, good spectral energy resolution if no source confusion; solid state detectors Scanning Sky Monitor (SSM ) Detect new X-ray transients, monitor known X-ray sources Soft X-ray Telescope (SXT) Soft X-ray energy; imaging in X-rays

Sun Avoidance Maneuver (SAM) – special sequencer implemented onboard to avoid Sun coming in the FOV of the P/L instruments during transition from one source to another Safe guarding P/L instruments from SAA - SAA entry/exit predicted on ground and by CPM; HV OFF and restored S/C Health monitoring and commanding - Main frame and Payload systems health monitored 24/7 with TTC support from BL4 station for all 14 orbits over a day. Payload events generated and uplinked one day in advance. Attitude maintenance - Gyro drift estimated continuously on ground and corrections uplinked to maintain pointing accuracy within the mission specification of ± 0.05 deg Ground segment hardware/software elements and interfaces –  Proposal uploading, validation, programming, command generation and uplink etc.,  Data download in every orbit, process, archive & disseminate  Assessment of dump quality and carrying out re-dump operation

Some Highlights - Science

Crab Nebula in high energy X-rays Detection of Gamma ray burst GRB A CZT detected a GRB Cadmium Zinc Telluride Imager (CZTI) Coded mask detector. First payload to be switched ON; Covers keV

Polarisation Marginal polarisation detected in GRB A (GCN 18422, Bhalerao et al. ) GRB A Polarisation of Compton scattered events Polarisation fraction % keV GCN 19011, S.V. Vadawale et al.

The fit significance as a function of trial period for the Crab pulsar observed by the CZTI during 12 November The abscissa shows the difference of the trial period from the average period during the 24-hour observation. The first half of the data clearly shows a period shorter than that in the second half of the data. The difference of 18 nanoseconds matches exactly the known rate of spin-down of the Crab Pulsar.

SSM observation of Crab nebula Scanning Sky Monitor (SSM) Coded mask detector; Covers keV

The brightest source with an X-ray intensity of ~2 Crab. Displays different types of light curves which changes within few days. SSM observation of GRS Scanning Sky Monitor (SSM) Coded mask detector; Covers keV Black hole source GRS observations by SSM

LAXPC observed Cyg X-1 Large Area X-Ray Proportional Counter (LAXPC); 3 – 80 keV Fast time variability; wide band spectral coverage Intensity variations observed at few seconds level from Cyg X-1, a black hole binary

Continuum spectrum of GRS obtained with one of the LAXPC unit. The top panel shows the observed points with a fit line. Bottom panel shows the residuals of observed points with respect to the fit. The residual figure is checked for goodness of fit. Spectrum of Crab

Timing of Crab pulsar

SXT observation of a PKS Soft X-ray Telescope (SXT) keV. X-ray optics developed in India The source strength (for events of 0-12 type) ~5 cps, background being <~ 0.1 cps, consistent with the source being in a low state.

X-ray Spectrum of Tycho supernova remnant using SXT; emission lines from ionized Mg, Si, S, Ar, Ca in the millions of degrees hot plasma can be seen clearly, the most prominent line being that of ionized Silicon. Spectrum of Tycho supernova remnant

Open cluster NGC 188 in our Galaxy located ~ 6000 light years away; Has ~1500 stars UVIT Observations NUVFUV VIS

NUV Image of the NGC 2336 galaxy (about 100 million light years away) in the sky acquired on Dec. 17, 2015.

NGC 2336 in FUV

ASTROSAT – All set to explore the deep space… Crossed more than 150 days in Orbit

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 –Slew mode observations –Observation time is planned to be made open to Indian Scientists after first year of performance verification and international users after second year, on proposal basis.