{
  "bibcode": "2009GCN..8971....1V",
  "body": "A.J. van der Horst (NASA/MSFC/ORAU) reports on behalf of the\nFermi GBM Team:\n\n\"At 18:25:07.19 UT on 9 March 2009, the Fermi Gamma-ray Burst Monitor\n(GBM) triggered and located GRB 090309B (trigger 258315909 / 090309.767).\nThe on-ground calculated location, using the Fermi GBM trigger data,\nis RA = 168.4, Dec = -55.0 (J2000 degrees, equivalent to\nJ2000 11h13m, -55d01'), with a statistical uncertainty of 2.6 degrees\n(radius, 1-sigma containment, statistical only; there is additionally\na systematic error which is currently estimated to be 2 to 3 degrees).\nThe angle from the Fermi LAT boresight is 26 degrees.\n\nThe GBM light curve consists of two main peaks, with durations of ~10\nand ~25 seconds, and no significant emission above background level in\nbetween for ~25 seconds. The time-averaged spectrum over the two peaks,\nfrom T0-4.1 to T0+5.1 s and from T0+32.8 to T0+54.3 s, is best fit by\na power law with an exponential high-energy cutoff. The index is\n-1.52 +/- 0.10 and the cutoff energy, parameterized as Epeak, is\n197 +/- 65 keV (chi squared 358 for 360 d.o.f.). The fluence\n(8-1000 keV) in this time interval is (4.7 +/- 0.4)E-6 erg/cm^2.\nThe 1-sec peak photon flux measured starting from T0+37.9s in the\n8-1000 keV band is 4.43 +/- 0.17 ph/s/cm^2.\n\nThe spectral and temporal analysis results presented above are preliminary;\nfinal results will be published in the GBM GRB Catalog.\"",
  "circularId": 8971,
  "createdOn": 1236701520000,
  "email": "Alexander.J.VanDerHorst@nasa.gov",
  "subject": "GRB 090309B: Fermi GBM detection",
  "submitter": "Alexander van der Horst at NASA/MSFC  <Alexander.J.VanDerHorst@nasa.gov>",
  "eventId": "GRB 090309B"
}