TITLE: GCN CIRCULAR NUMBER: 11423 SUBJECT: GRB 101123A: Fermi GBM detection DATE: 10/11/25 01:16:48 GMT FROM: Sylvain Guiriec at UAH Sylvain Guiriec (UAH) reports on behalf of the Fermi GBM Team: At 22:51:34.97 UT on 23 November 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 101123A (trigger 312245496 / 101123952). The on-ground calculated location, using the GBM trigger data, is RA = 131.24, DEC = 6.51 (J2000 degrees, equivalent to 08 h 54 m 27 s, 06 d 30 ' 36 ''), with an uncertainty of 1 degree (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 86 degrees. GBM triggered on a weak pulse followed by three separate emission periods with a total duration (T90) of about 105 s (50-300 keV). The time-averaged spectrum of the brightest part of the burst from T0+42 s to T+57 s is adequately fit by a Band function with Epeak = 476 +/- 11 keV, alpha = -0.75 +/- 0.01, and beta = -2.14 +/- 0.03. The event fluence (10-1000 keV) over the T90 duration is (1.283 +/- 0.006)E-4 erg/cm^2. The 1-sec peak photon flux measured starting from T0+51.7 s in the 8-1000 keV band is 49 +/- 2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog.