Highlights of the ASTROSAT Mission

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

2. ASTROSAT Space astronomy observatory of India • India’s multiwavelength space astronomy mission is aimed at studying the celestial sources in X-ray (0.3 - 100 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 (www.isro.gov.in).

3. 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. Lift-off from SHAR at 10:00 hrs IST on 28th Sep 2015

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

5. Mission details

6. 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)

7. 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;

8. Broadband coverage in a single mission LAXPC CZTI X-ray, Ultraviolet and limited optical Photon energy (keV) SXT SSM 10-3 10-2 10-1 1 101001000 UV UVIT Extreme UV Hard X-rays Visible Gamma rays Soft X-rays IR 103 102 101 100 10-1 10-2 10-3 Wavelength (nm) Typical Electromagnetic Spectrum

9. 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.

10. Highlights - Operations

11. S/C in axes defined configuration

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

13. Sun Avoidance Maneuver (SAM) – special sequencer implemented onboardto 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

14. Some Highlights - Science

15. CZT detected a GRB Cadmium Zinc Telluride Imager (CZTI) Coded mask detector. First payload to be switched ON; Covers 25 - 150 keV Crab Nebula in high energy X-rays Detection of Gamma ray burst GRB 151006A

16. Polarisation • Marginal polarisation detected in GRB 151006A (GCN 18422, Bhalerao et al. ) • GRB 160131A • Polarisation of Compton scattered events • Polarisation fraction- 50-60% -- 100-300keV • GCN 19011, S.V. Vadawale et al.

17. The fit significance as a function of trial period for the Crab pulsar  observed by the CZTI during 12 November 2015.  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.

18. SSM observation of Crab nebula Scanning Sky Monitor (SSM) Coded mask detector; Covers 2.5 - 10 keV

19. SSM observation of GRS Scanning Sky Monitor (SSM) Coded mask detector; Covers 2.5 - 10 keV Black hole source GRS 1915+105 observations by SSM The brightest source with an X-ray intensity of ~2 Crab. Displays different types of light curves which changes within few days.

20. 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

21. Continuum spectrum of GRS 1915+105  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

22. Timing of Crab pulsar

23. SXT observation of a PKS2155-304 Soft X-ray Telescope (SXT) 0.3- 8 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.

24. Spectrum of Tycho supernova remnant 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.

25. UVIT Observations NUV FUV Open cluster NGC 188 in our Galaxy located ~ 6000 light years away; Has ~1500 stars www.isro.gov.in VIS

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

27. NGC 2336 in FUV

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

29. 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 calibrationand for maintaining the health of the instruments • Slew mode observations • Observation time is planned to be made opento Indian Scientists after first year of performance verification and international users after second year, on proposal basis.