{
  "bibcode": "2012GCN.13819....1C",
  "body": "The GBM Team reports:\n\n\"At 21:03:03.77 UT on 21 September 2012, the Fermi Gamma-Ray Burst Monitor\ntriggered and located GRB 120921A (trigger 369954186 / 120921877).\n\nThe on-ground calculated location, using the GBM trigger data, is\nRA = 96.4, DEC = -64.8 (J2000 degrees, equivalent to 06 h 26 m,  -64 d \n48 '),\nwith an uncertainty of 3.2 degrees (radius, 1-sigma containment,\nstatistical only; there is additionally a systematic error which is \ncurrently estimated\nto be 2 to 3 degrees).\n\nThe angle from the Fermi LAT boresight is 110 degrees.\n\nThis is a single-peaked burst with a duration (T90) of about\n6 s (50-300 keV), with a moderate fluence (10-1000 keV) of about 2.5E-6 \nerg/cm^2.\n\nGRB 120921A is not a particularly interesting GRB except for the fact that\nit is the 1000th GRB which triggered GBM.  It occurred after 4 years,\n2 months, and 1 week of Fermi GBM operations.  The annual GBM\ndetection rate of 240 GRBs compares with 280 GRBs detected annually\nby BATSE.  Although GBM has much less effective area than BATSE, its\nversatile triggering scheme leads to more detections than expected\nfrom scaling the BATSE rate by the relative collection areas.\n\nGBM burst locations are distributed via GCN notices on timescales of\nseconds after the trigger (Flight Software and Ground Automated),\nwith Human-in-the-loop final locations distributed as GCN notices\nbetween 20 minutes and several hours after the trigger.  Recent\nimprovements in the ground processing of locations have led to a\ndecrease in processing time for the Ground Automated locations so that\nmost appear within 30 seconds of trigger time.\n\nFinal spectral results for this and all GBM GRBs will be published in the\nGBM GRB Catalog.  Data from from the first ~500 GBM GRBs appear\nin the first GBM GRB catalogs:\n\nPaciesas, W.S. et al. 2011, ApJS, 199, 18 (general)\nGoldstein, A. et al. 2011, ApJS, 199, 19 (spectral).\n\nPreliminary duration, flux, and fluence information for all GBM GRBs is \navailable\nat the HEASARC in the days - week following the trigger\ntime:  http://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html\"\n\n------------------------------------------------------------------------",
  "circularId": 13819,
  "createdOn": 1348674102000,
  "email": "valerie.connaughton@nasa.gov",
  "subject": "GRB 120921A: Fermi GBM detection of its 1000th GRB",
  "submitter": "Valerie Connaughton at UAH/NSSTC  <valerie.connaughton@nasa.gov>",
  "eventId": "GRB 120921A"
}