 of the Sky

1. K. Malek1),L.W. Piotrowski2), M. Biskup2), M. Cwiok2), M.Denis3), W. Dominik2), J.Grygorczuk3), G.Kasprowicz4), J.Juchniewicz3), M. Kwiatkowski4), A. Majczyna5), A. Majcher1), L. Mankiewicz1), M. Molak4), K. Nawrocki5), R. Pietrzak3), K. Pozniak4), R. Romaniuk4), D. Rybka5), P. Sitek5), M. Sokolowski5), J. Uzycki4), P. Wawer3), R. Wawrzaszek3), G. Wrochna5), M. Zaremba4), A.F. Zarnecki2) 1) Center for Theoretical Physics, Polish Academy of Sciences; 2) Institute of Experimental Physics, University of Warsaw; 3)Space Research Centre, Polish Academy of Sciences; 4) Warsaw University of Technology;5) Soltan Institute for Nuclear Studies; Special thanks to prof. B. Paczynski (Princeton University) and G. Pojmanski (Warsaw University) and all staff of the Las Campanas Observatory. 0  of the Sky Always on time! Innovative approach to GRB optical counterparts and other short optical transients detection Study of astrophysical phenomena with time scale from seconds to months We present an innovative approach to the GRB optical counterparts observations, which ought to overcome one of the main obstacles towards deeper understanding of GRB phenomenon: only a few observations in the very early stage of the burst. The “ of the Sky” introduces the idea of constant, high time resolution, large sky area monitoring. Efficient data stream reduction algorithms were created for optical transient detections not depending on GRB satellites. SCIENTIFIC GOALS GRB prompt optical emission (even prior to  burst) AGN/blasar monitoring participation in multiwavelength campaigns search for new fast varying objects flare star outburst variable stars (including novae) NEW APPROACH continuous large sky area monitoring images prior to satellite triggers self-triggering high time resolution Final mount design FULL SYSTEM (under construction) • 2 matrices of 16 CCD cameras, 2000x2000 pixels, • lenses: Canon EF f=85mm, f/d=1.2, • matrices outlied by ~50 km, working in coincidence • FoV: 16 × 20o×20o = 2 steradians: • = GLAST FoV, > Swift BAT FoV • limiting mag.: ~14m (1 frame 10s), ~15m (10 co-added frames) • first data expected in fall 2007 FIRST RESULTS (from prototype) Search for GRB optical counterparts: 217 GCN alerts received (>7.2004): 9 apparatus off 11 clouds 59 below horizon 103 daytime 32 FoV change required 3 inside current FoV limits 9m – 14.3m published: GRB 040916, 041217, 050123, 050326, 050607, 060607, 060719, 061202, 070521 limits during the burst: GRB 040825A, GRB 050412 PROTOTYPE • working from 07.2004 at Las Campanas Observatory, Chile, • 2 CCD, 2000x2000 pixels each, • lenses: Zeiss , f=85mm, f/d=1.2 • FoV: 21o×21o, 1 pixel = 36'' • limiting mag.: • 11-13m (1 frame 10s),13-14m (20 frames) Search for optical flashes: 132 flashes < 10s detected (may be flashing satellites) 8 flashes >10s detected (including flare of CN Leo) Outburst of CN Leo flare star, automatically detected on-line. Star was not visible in our range before its outburst, thus it well simulates expected behavior of GRB optical counterpart. Modes of observation The prototype system works autonomously, according to schedule, which could be changed via Internet: follows SWIFT or Integral FoV independently detects optical flashes in real time (self-triggering) instantaneously follows satellite alerts distributed by GCN performs dedicated observations of interesting objects (eg. blasars, quasars, novae) in spare-time twice a night makes a full sky survey (2x40 min) IS OUR RANGE SUFFICIENT? Knowledge about early brightness is weak, for most optical counterparts were observed long after GRB. How to estimate number of bursts expected in “ of the Sky” range? • On-line data stream reduction • 3000 frames/night, 1 frame = 8 MB -> 25 GB/night • (full system: 32x25 GB = 800 GB/night) • algorithms inspired by particle physics – multilevel trigger: • Level 1 – very fast and simple single pixel analysis • Level 2 – sophisticated object analysis Number of objects per night at different trigger steps. Level 1 consists of very fast and simple cuts mainly for eliminating constant stars and apparatus effects. Coincidence performed at the last step of Level 1 mainly eliminates cosmic ray effects. Level 2 eliminates real objects like satellites, planes and meteors not reduced by Level 1. Results of extrapolation of 45 early lightcurves (<5000s) to 30 s after GRB. The average brightness, not filter corrected, is. 15.7m. (data from GRBlog). Dashed lines – our limits with and without filter correction. Maximal GRB optical counterpart brightness in the first 100 s after GRB, for 39 bursts. The average brightness, not filter corrected, is 15.9m (data from GRBlog). Both the extrapolation and the real maximal magnitude show, that we should be able to see close to one third of the GRB optical counterparts (during night, in our hemisphere). That is very optimistic! http://grb.fuw.edu.pl