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Prompt optical observations of GRBs with "Pi of the Sky" system

Marcin Sokolowski on behalf of “Pi of the Sky” collaboration Institute for Nuclear Studies, Warsaw, Poland. Prompt optical observations of GRBs with "Pi of the Sky" system. http://grb.fuw.edu.pl. The Sixth Huntsville Gamma-Ray Burst Symposium 20 – 23 October 2008. “Pi of the Sky” project.

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Prompt optical observations of GRBs with "Pi of the Sky" system

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  1. MarcinSokolowski on behalf of “Pi of the Sky” collaboration Institute for Nuclear Studies, Warsaw, Poland Prompt optical observations of GRBs with "Pi of the Sky" system http://grb.fuw.edu.pl The Sixth Huntsville Gamma-Ray Burst Symposium 20 – 23 October 2008

  2. “Pi of the Sky”project

  3. Project inspired by prof. Bohdan Paczyński “Pi of the Sky” collaboration Dr. Grzegorz WrochnaThe Andrzej Sołtan Institute for Nuclear Studies Dr. Lech MankiewiczCenter for Theoretical Physics, Polish Academy of Science Prof. Filip Żarnecki Institute of Experimental Physics, Warsaw University Warsaw University of Technology : - Faculty of Physics - Institute of Electronic Systems Space Research Center Faculty of Mathematics, Informatics and Mechanics, Warsaw University Pedagogical University of Cracow Cardinal Wyszyński University

  4. Prompt optical observations of GRBsThere are only a few events with optical observations during gamma-ray emission Continuous monitoring of large fraction of the sky in short time scales ( ≥ 10 sec ) Automatic identification of short optical flashes Identification of nova stars Analysis of variable stars and flare stars Motivation

  5. Hunting for prompt optical emission GRB 041219 - triggered by precursor GRB 990123 - reached very quickly GRB 080319B - triggered by GRB 080319A NEW APPROACH IS NEEDED TO OBSERVE PROMPT OPTICAL SIGNAL

  6. “Pi of the Sky” system Parallax ~ 150 km to reject close optical flashes SITE A SITE B • Continuous monitoring of large part of the sky ( ~ 1 / 6 ). Corresponding to FOV of the SWIFT • Short exposures (10 s), large data stream ~1TB / night ! • Every GRB detected by these satellites will by in our FOV ( reaction time < 0 ! ) • Own real time trigger for optical flashes, parallax to reject near Earth objects ( artificial satellites )

  7. Custom designed cameras, Canon objectives, f = 85 mm, f/d = 1.2, resolution 36'' Ethernetand USB2.0 interface STA 0820 chip , 2k x 2k , 2 side readout 1Mhz ( 1sec ) Readout noise < 30e- Programmable electronics ( FPGA ) 2 stage thermoelectric cooling Shutter designed for ≥ 107 cycles System is under construction

  8. Prototype in Las CampanasObservatory in Chile

  9. Prototype system in Las Campanas Observatory ( LCO ) in Chile Working since June 2004 Prototype systemin LCO • 2 cameras on paralactic mount working in coincidence • Fully autonomous system • Optics same as final cameras • IR-cut filter ( R to be installed ) • CCD 0442A Firechild 2k x 2k • Field of View ~ 20o x 20o • 10s exposures • Limiting magnitude : ~11m on 10 sec exposure ~13m on 20 averaged images

  10. 10s exposures, 2s dead time Follow FOV of SWIFT, INTEGRAL or GLAST ( soon ) if not possible follow objects from GTN and WEBT list of interesting objects ( blazars, AGNs etc ) On-line flash recognition algorithm looks for short timescale OTs Reacts to alerts from GCN Evening and morning all sky scan Observation strategy SWIFT

  11. Data Analysis

  12. On-line Data Analysis • MAIN GOAL : Identify short optical flashes (δT ≥ 10 sec ) in real time • Compares new image with series of previous images andfinds new objects in the sky • Flash recognition trigger based on idea multilevel triggering systems used in particle physics • Rejection of background events, like flashing artificial satellites, cosmic rays, stars, meteors, clouds, UFOs etc.

  13. Cuts in flash recognition algorithm

  14. Examples of background events “Star Wars” like background Meteors

  15. 2 sure events – GRB080319B and outburst of flare star CN Leo 8 flashes visible on 2 consecutive images, but single camera 150 flashes visible on both cameras, but single 10s exposure On-line Data Analysis Results -1 0 +1 +2 +3 +4

  16. GRB080319B

  17. Early morning 19th of March 2008 ... At 6:12:49 UT second gamma-ray burst GRB080319B at :λ = 14h31m42s δ = +36o18'10''Closer then 12o from first one and still in the FOV of the “Pi of the Sky” system At 5:45:42 UT first gamma-ray burst GRB080319A at :λ = 13h45m25s δ = +44o04'22'' “Pi of the Sky” telescope repointed to have it in the center

  18. A naked-eye burst GRB080319b GRB in the center :6:14:03 - 06:15:56 • Automatically identified by on-line flash recognition algorithm • Optical observation before and during gamma emission with 10stime resolution • Peak brightness 5.3m • The brightest optical and X-ray event ever observed • Unprecedented coverage of optical light curve • Published in Nature 11 Sept2008 , Vol. 455 No. 7210

  19. Coverage of the optical lightcurve

  20. LIMITS ON OTHER GRBs

  21. GRB observations 89 + 241 GRBs in 06.2004 – 07.2005 & > 06.2006 2+2 inside FOV limits : before / during / after : • GRB 080319b : >11.5 m / max @ 5.3 m / • GRB 040825A ( GCN 2677 ) : >10.0m / >12.0m / > 9.5m • GRB 050412 ( GCN 3240 ) : >11.5m / > 11.0m / > 11.5m • GRB 070521 ( GCN 6437 ) : >12.2m / >12.6m / > 12.5m 16 + 46 outside FOV limitis after , 9 GCN published : • GRB 080805 > 12.5m ( GCN 8063 ) • GRB 061202 > 14.0m ( GCN 5891 ) • GRB 060719 > 12.5m ( GCN 5346 ) • GRB 060607 > 13.4m ( GCN 5241 ) • GRB 050607 > 12.5m ( GCN 3526 ) • GRB 050326 > 11.0m ( GCN 3146 ) • GRB 050123 > 12.0m ( GCN 2970 ) • GRB 041217 > 11.5m ( GCN 2862 ) • GRB 040916 > 13.0m ( GCN 2725 ) 5+27 – clouds or apparatus off66+166 – daytime or below horizon

  22. PREDICTIONS FOR THE FINAL SYSTEM

  23. Hoping to see more soon ... According to optical lightcurves of observed GRBs, number of possible positive detections by full “Pi of the Sky” was estimated About18 % of all bursts when extrapolated to the time T=0 is near the limiting magnitude of the “Pi of the Sky” system

  24. GLAST satellite was launched ( June 11th 2008 ) There is a chance to observe short GRBs ( at least give limits at time T=0 ) Conservative preditions for number of observations with the final system The final number of events can be larger, because :

  25. Summary • Large FOV allowed for prompt optical observation of GRB 080319B before, during and after the burst • Final “Pi of the Sky” system is under construction and we are looking for a good place for it ... • It will be able to automatically detect short optical flashes • And observe GRBs with negative reaction time • We plan to start collecting data with the final system in 2009 • And hope to have more early optical observations • Prototype in LCO is working and identifying short opticaltransients which we regularly publish on our web page : http://grb.fuw.edu.pl

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