7 March 2008Nicola Galante, DPG - Freiburg1 Observation of GRBs with the MAGIC Telescope Nicola Galante (MPI für Physik - München) for the MAGIC Collaboration

7 March 2008Nicola Galante, DPG - Freiburg2 Observations at VHE BATSE: 2704 GRB up to ~2 MeV EGRET: 4 GRBs above 1 GeV (up to 18 GeV) No more detections above GeV (only 1 evidence of excess by MILAGRO) (too) Many emission models New phenomenology recently discovered (GRB late X-ray flares s later) VHE observations necessary to constrain models GeV/TeV emission present in late activity? AGILE already in orbit, GLAST will be launched soon - GeV observations time! GeV/TeV observation possible by new generation IACTs too

7 March 2008Nicola Galante, DPG - Freiburg3 Constraints on IACT Isotropic GRB distribution: IACT Duty-Cycle ~10% Duration Short T 90 < 2s,  T 90   0.7s, 1/3 Tot Long T 90 > 2s,  T 90   30s, 2/3 Tot Fast repositioning time required!

7 March 2008Nicola Galante, DPG - Freiburg4 Constraints on IACT Band function valid up to GeV E break  300 keV hard-to-soft evolution well described by Shock Synchrotron Model (SSM) moreover… Tavani M., Ap.J. 466, (1996)

7 March 2008Nicola Galante, DPG - Freiburg5 Afterglow and redshift GRB970228: first fading X-ray counterpart by Beppo-SAX. From X to O up to several days adjacent galaxies: red-shift measurement 0.01 ≤ z ≤ 6.29 Jakobsson P., Levan A., et al., A&A 447, , 2006

7 March 2008Nicola Galante, DPG - Freiburg6 Interaction with EBL cosmological horizon Observed flux is attenuated z max  1 for 50 GeV threshold K. Mannheim et al., A&A, 413, (2006)

7 March 2008Nicola Galante, DPG - Freiburg7 GRB Alarm System GC N Alert System Central Control Communication: web Acoustic alarm Outside MAGIC systems

7 March 2008Nicola Galante, DPG - Freiburg8 The MAGIC Telescope Analog signal transport via optical fibers 2-level trigger system & 2 GHz FADC system Active mirror control (PSF: 90% of light in 0.1 o inner pixel) high reflective diamond milled aluminum mirrors Light weight Carbon fiber structure for fast repositioning o FOV camera high QE PMTs (QE max = 30% 330 – 450 nm)

7 March 2008Nicola Galante, DPG - Freiburg9 Sensitivity Since February 2007 a fast 2GHz Multiplexed FADC DAQ system is working  improved sensitivity Current Sensitivity for E>300 GeV 1.57% Crab in 50 h

7 March 2008Nicola Galante, DPG - Freiburg10 Sensitivity Test on Crab Nebula: measured sensitivity as a function of observation time 70 GeV < E < 300 GeV ~3.6 Crab in 20 s

7 March 2008Nicola Galante, DPG - Freiburg11 Observed GRBs GRBt0t0  t alert  t oss t :11:5258 s108 s10 s50° a02:13:5640 s269 s20 s42° :22:21540 s717 s60 s55° a01:46:2916 s131 s12 s50° a04:29:0213 s40 s70 s49° :51:4482 s145 s225 s20° :24:5415 s583 s2 s42° :55:35171 s259 s83 s44° :46:5316 s52 s11 s10° Typical repointing 40÷50 s

7 March 2008Nicola Galante, DPG - Freiburg12 Two Prompt Emissions GRB a GRB

7 March 2008Nicola Galante, DPG - Freiburg13 Flux Upper Limits GRBE th Flux UL (30 min) GeV0.2 CU a152 GeV0.3 CU GeV0.8 CU a215 GeV0.4 CU a170 GeV0.8 CU GeV0.3 CU GeV0.4 CU GeV1.7 CU GeV0.4 CU

7 March 2008Nicola Galante, DPG - Freiburg14 Flux Upper Limits GRBt0t0  t alert  t oss t :59:5819 s57 s8 s28° :26:22140 s169 s106 s38° :40:0813 s786 s0.4 s56° :27:03674 s701 s34 s35° a04:00:13539 s680 s56 s52° GRBE th Flux UL (30 min) GeV0.7 CU GeV0.8 CU GeV0.5 CU GeV0.2 CU a GeV0.4 CU

7 March 2008Nicola Galante, DPG - Freiburg15 Conclusions MAGIC features (TESTED!): Flux sensitivity:  LiMa in 70 GeV < E < 300 GeV Angular resolution: 0.1° Slewing capabilities: 40÷50 s, ~20x than other Cherenkov E th : 50 GeV at zenith, lowest attained E at Cherenkov Publishing GCN circular within 1 week! Paper on observations already published J. Albert, et al., Ap. J. 667, 358, 2007 Measurements in VHE crucial but need a near (but not so much) GRB!

7 March 2008Nicola Galante, DPG - Freiburg16 Fast Slewing Time!