GCN Circular 8723
Colleen Wilson-Hodge (MSFC) and Valerie Connaughton (UAH) on behalf of the Fermi-GBM team, Francesco Longo (INFN Trieste) and Nicola Omodei (INFN Pisa) on behalf of the Fermi LAT team. "On 21:17:55.41 UT of Dec 24 2008 GBM detected a bright GRB. Preliminary analysis of the real-time Fermi GBM data from Trigger number 251846276/ GRB 081224887 / GRB 081224 shows that this is a FRED (Fast Rise Exponential Decay) lasting approximately 50 seconds with a peak of FWHM 15 sec long. It is located to a position of RA=206.2, Dec= 73.3 with statistical uncertainty 1 deg (and an estimated systematic uncertainty of 2-3 deg) which places it at 16 deg to the LAT boresight. The Large Area Telescope (LAT) also provided a tentative onboard localization: RA=213.367, DEC=74.233 (J2000) corresponding to: RA: +14h 13m 28s (J2000), DEC: +74d 13' 60" (J2000) with on board estimated error of 36 arcmin (statistical only). The current estimated onboard systematic error is 1 deg. The estimated LAT position is 2.2 deg from the ground GBM location and may be considered more reliable. Accurate LAT localization and spectral analysis will await the downlink of both LAT and GBM data which could take several hours. We further report that the Fermi Observatory executed a maneuver following this trigger and will track the burst location for the next 5 hours, subject to Earth-angle constraints. We encourage follow up observations. The Fermi LAT point of contact for this burst is Francesco Longo (firstname.lastname@example.org). The Fermi GBM point of contact is Valerie Connaughton (email@example.com) The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. This message can be cited."