{
  "bibcode": "2009GCN..9294....1B",
  "body": "Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team:\n\n\n\"At 10:34:38.46 UT on 28 April 2009, the Fermi Gamma-Ray Burst Monitor\ntriggered and located GRB 090428 (trigger 262607680 / 090428441).\nThe on-ground calculated location, using the GBM trigger\ndata, is RA = 212.4, DEC = +37.3 (J2000 degrees,\nequivalent to 14h 10m, 37d 18'), with an uncertainty\nof 3.5 degrees (radius, 1-sigma containment,\nstatistical only; there is additionally a systematic\nerror which is currently estimated to be 2 to 3 degrees).\n\nThe angle from the Fermi LAT boresight is 96 degrees.\n\nThe GBM light curve consists of two peaks\nwith a duration (T90) of about 8 s (8-1000 keV).\nThe time-averaged spectrum from T0-0.51 s to T0+2.04 s is\nadequately fit by a power law function with an exponential\nhigh energy cutoff.  The power law index is -0.59 +/- 0.16\nand the cutoff energy, parameterized as Epeak, is\n97 +/- 7 keV (chi squared 471 for 485 d.o.f.).\n\nThe event fluence (8-1000 keV) in this time interval is\n(9.9 +/- 1.4)E-07 erg/cm^2. The 128-msec peak photon flux measured\nstarting from T0+1.4 s in the 8-1000 keV band\nis 12.3 +/- 1.9 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\n(chi squared 468 for 484 d.o.f.) with Epeak = 85 +/- 10 keV,\nalpha= -0.40 +/- 0.25 and beta = -2.7 +/- 0.4.\n\n\nThe spectral analysis results presented above are preliminary; \nfinal results will be published in the GBM GRB Catalog.\"",
  "circularId": 9294,
  "createdOn": 1241018435000,
  "email": "ebs@mpe.mpg.de",
  "subject": "GRB 090428: Fermi GBM detection",
  "submitter": "Elisabetta Bissaldi at MPE  <ebs@mpe.mpg.de>",
  "eventId": "GRB 090428"
}