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
(francesco.longo@ts.infn.it).
The Fermi GBM point of contact is Valerie Connaughton
(valerie@nasa.gov)

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."