{
  "bibcode": "2009GCN..9764....1C",
  "body": "Carosi A. (INAF Rome), Gaug M. (IAC Tenerife),\nAntonelli L.A. (INAF Rome), Bastieri D. (Univ. Padova),\nBecerra Gonzalez J. (IAC Tenerife), Covino S. (INAF Rome),\nGalante N. (MPI Munich), Garczarczyk M. (IFAE Barcelona),\nLa Barbera A. (INAF Palermo), Longo F. (INFN Trieste),\nScapin V. (Univ. Udine) and Spiro S. (INAF Rome)\nfor the MAGIC collaboration\n\nThe MAGIC Imaging Atmospheric Cherenkov Telescope performed a follow-up\nobservation of the BAT short burst GRB090621B (Curran et al., GCN Circ. \n9545). The burst was also triggered by Fermi-GBM (Goldstein et al., GCN \nCirc. 9562). We received the GCN alert at 22:07:38 UT (T0+13s). Data\ntaking with MAGIC started at 22:43:33 UT (T0+2169s), when the GRB zenith\nangle went below 60 degrees. The observation continued for 12570 s.\n\nNo evidence for VHE gamma-ray emission above the analysis threshold was \nfound.\n\nA preliminary analysis, for the hypothesis of steady emission and\nassumption of a differential photon spectral index of -2.5, yields the\nfollowing 95% CL differential flux upper limits, including a 30%\nsystematic uncertainty on the telescope efficiency.\n\nBecause of improving sensitivities and analysis threshold due to \ndecreasing zenith angle during the observation, the data sample\nwas split into 4 parts:\n\nE ( 300-1000 GeV): 0.42 * 10^-10 erg cm^-2 s^-1\nfor a time window from 22:43:33 UT to 23:38:37 UT\nAnalysis threshold: 407 GeV\n\nE ( 175- 300 GeV): 5.61 * 10^-10 erg cm^-2 s^-1\nE ( 300-1000 GeV): 0.19 * 10^-10 erg cm^-2 s^-1\nfor a time window from 23:38:37 UT to 00:32:31 UT\nAnalysis threshold: 291 GeV\n\nE ( 175- 300 GeV): 4.97 * 10^-10 erg cm^-2 s^-1\nE ( 300-1000 GeV): 0.24 * 10^-10 erg cm^-2 s^-1\nfor a time window from 00:32:31 UT to 01:23:06 UT\nAnalysis threshold: 224 GeV\n\nE ( 125- 175 GeV): 15.27 * 10^-10 erg cm^-2 s^-1\nE ( 175- 300 GeV):  1.25 * 10^-10 erg cm^-2 s^-1\nE ( 300-1000 GeV):  0.22 * 10^-10 erg cm^-2 s^-1\nfor a time window from 01:23:06 UT to 02:13:04 UT\nAnalysis threshold: 186 GeV\n\nWe can also exclude emission of a constant flux in any 100s time bin\nsmaller than:\n\nE ( 300-1000 GeV): 4.02 * 10^-10 erg cm^-2 s^-1\nfor a time window from 22:43:33 UT to 23:38:37 UT\nAnalysis threshold: 407 GeV\n\nE ( 175- 300 GeV): 23.60 * 10^-10 erg cm^-2 s^-1\nE ( 300-1000 GeV):  1.52 * 10^-10 erg cm^-2 s^-1\nfor a time window from 23:38:37 UT to 00:32:31 UT\nAnalysis threshold: 291 GeV\n\nE ( 175- 300 GeV): 15.33 * 10^-10 erg cm^-2 s^-1\nE ( 300-1000 GeV):  1.41 * 10^-10 erg cm^-2 s^-1\nfor a time window from 00:32:31 UT to 01:23:06 UT\nAnalysis threshold: 224 GeV\n\nE ( 125- 175 GeV): 22.23 * 10^-10 erg cm^-2 s^-1\nE ( 175- 300 GeV):  7.87 * 10^-10 erg cm^-2 s^-1\nE ( 300-1000 GeV):  1.15 * 10^-10 erg cm^-2 s^-1\nfor a time window from 01:23:06 UT to 02:13:04 UT\nAnalysis threshold: 186 GeV\n\nThis message can be cited.",
  "circularId": 9764,
  "createdOn": 1249974646000,
  "email": "garcz@mppmu.mpg.de",
  "subject": "GRB 090621B: MAGIC telescope GeV observation",
  "submitter": "Markus Garczarczyk at MPI/MAGIC  <garcz@mppmu.mpg.de>",
  "eventId": "GRB 090621B"
}