TITLE: GCN CIRCULAR NUMBER: 11600 SUBJECT: GRB 110123A: Fermi GBM detection DATE: 11/01/25 00:31:13 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (USRA) and D. Gruber (MPE) report on behalf of the Fermi GBM Team: "At 19:17:45.03 UT on 23 January 2011, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 110123A (trigger 317503067 / 110123804). The on-ground location, using the GBM trigger data, is RA = 247.0, Dec = +28.0 (J2000 degrees, equivalent to 17h40m, +28d02'), with an uncertainty of 1.64 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 58 degrees. This GRB was bright enough to result in a Fermi spacecraft repointing maneuver. The GBM light curve consists of one main peak with substructure, with a duration (T90) of 17.9 +/- 0.8 s (50-300 keV). The time-averaged spectrum from T0-1.8 s to T0+22.8 s is best fit by a Band function with Epeak = 280 +/- 15 keV, alpha = -0.64 +/- 0.03, and beta = -1.96 +/- 0.05. The event fluence (10-1000 keV) in this time interval is (2.61 +/- 0.03)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+8.4 s in the 10-1000 keV band is 8.3 +/- 0.2 ph/s/cm^2. The temporal and spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."