//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10457 SUBJECT: GRB 100224B: Fermi GBM detection DATE: 10/02/26 15:58:41 GMT FROM: Suzzanne Foley at MPE Suzanne Foley (MPE) reports on behalf of the Fermi GBM Team: "At 02:40:55.48 UT on 24 February 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100224B (trigger 288672057 / 100224112). The on-ground calculated location, using the GBM trigger data, is RA = 269.56, DEC = -17.08 (J2000 degrees, equivalent to 17 h 58 m, -17 d 05 '), with an uncertainty of 1.6 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 88 degrees. The GBM light curve consists of 3 peaks with a duration (T90) of about 77 (+/-2) s (50-300 keV) starting at T0-5.6 s. The time-averaged spectrum from T0-7.2 s to T0+71.7 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -1.36 (+0.07/-0.06) and the cutoff energy, parameterized as Epeak, is 181.40 (+31.50/-23.60) keV (CSTAT 591 for 361 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.08 +/- 0.05 )E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+16.4 s in the 8-1000 keV band is 10.7 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." [GCN OPS NOTE(26feb10): The administrator corrected the mistaken first name of the author. Apologies.]