//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9929 SUBJECT: GRB 090922A: Fermi GBM detection DATE: 09/09/23 07:26:52 GMT FROM: Arne Rau at MPE Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "At 12:56:42.14 UT on 22 September 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090922A (trigger 275317004 / 090922539). The on-ground calculated location, using the GBM trigger data, is RA = 17.1, DEC = 74.3 (J2000 degrees, equivalent to 17h 06m, 74d 18'), with an uncertainty of 1 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 19 degrees. Moreover, this burst was bright enough to result in a Fermi spacecraft re-pointing maneuver. The GBM light curve shows a bright peak of approximately 10s duration followed by a weaker pulse approx. 60s later. The burst duration (T90) is 92 +/ 3 s (8-1000 keV). The time-averaged spectrum of the main peak from T+0.003 s to T0+10.240 s is best fit by a Band function with Epeak = 139.3 +/- 6.6 keV, alpha = -0.77 +/- 0.05, and beta = -2.28 +/- 0.07 (chi squared 1217/921 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.14 +/- 0.02)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+2.048 s in the 8-1000 keV band is 15.6 +/- 0.04 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9930 SUBJECT: GRB090922A: correction to Fermi location DATE: 09/09/23 12:18:37 GMT FROM: Arne Rau at MPE Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "There has been a typo in the GBM localization of GRB 090922A (Rau, GCN#9929). The correct location is: RA=17.1deg (01h08min) and Dec=74.3deg (74d18') 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). I thank S. Holland for realizing this."