{
  "bibcode": "2010GCN.10568....1G",
  "body": "A. Goldstein (UAH) and D. Gruber (MPE) \nreport on behalf of the Fermi GBM Team: \n\n\"At 07:07:32.24 UT on 1 April 2010, the Fermi Gamma-Ray Burst Monitor\ntriggered and located GRB 100401A (trigger 291798454 / 100401297)\nwhich was also detected by the Swift-BAT (J.R. Cummings et al. 2010,\nGCN 10567).  The GBM on-ground location is consistent with the \nSwift-BAT position. The angle from the Fermi LAT boresight is 45 degrees.\n\nThe GBM light curve consists of an initial bright pulse at trigger time\nlasting ~4 s followed by a second, much softer pulse of ~30 s in duration,\napproximately 65 s after trigger time. The total duration (T90) is \nestimated to be about 100 s (8-1000 keV). The time-averaged spectrum of \nthe first pulse from T0-1.9 s to T0+3.2 s is best fit by a power law \nfunction with an exponential high energy cutoff.  The power law index is \n-1.49 +/- 0.17 and the cutoff energy, parameterized as Epeak, is \n144.90 +/- 62.20 keV (chi squared 439 for 483 d.o.f.). The first \npulse is equally well fit by a simple power law with index \n-1.77 +/- 0.06 (chi squared 444 for 484 d.o.f.).  The \ntime-averaged spectrum of the second pulse from T0+74.9 s to \nT0+98.4 s is well fit by a power law function with an exponential\nhigh energy cutoff.  The power law index is -1.52 +/- 0.39 and\nthe cutoff energy, parameterized as Epeak, is 29.34 +/- 8.96 keV\n(chi squared 511 for 483 d.o.f.).  The second pulse is equally well\nfit by a simple power law with index -2.16 +/- 0.11 (chi squared \n514 for 484 d.o.f.).\n\nThe event fluence (8-1000 keV) over the entire emission is \n(2.39 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured \nstarting from T0-1.4 s in the 8-1000 keV band \nis 3.61 +/- 0.16 ph/s/cm^2.\n\nThe spectral analysis results presented above are preliminary; \nfinal results will be published in the GBM GRB Catalog.\"",
  "circularId": 10568,
  "createdOn": 1270249148000,
  "email": "adam.m.goldstein@msfc.nasa.gov",
  "subject": "GRB 100401A: Fermi GBM detection",
  "submitter": "Adam Goldstein at Fermi-GBM/UAH  <adam.m.goldstein@msfc.nasa.gov>",
  "eventId": "GRB 100401A"
}