[vsnet-grb-info 7211] Fermi/GBM detection of GRB 081225

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8784
SUBJECT: Fermi/GBM detection of GRB 081225
DATE:    09/01/07 16:46:18 GMT
FROM:    Chryssa Kouveliotou at MSFC  <chryssa.kouveliotou at nasa.gov>

Chryssa Kouveliotou (NASA/MSFC), Valerie Connaughton (UAHuntsville) report on behalf of the Fermi GBM Team: 

"At 06:09:21.34 UT on 25 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081225 (trigger 251878162/081225256).

The on-ground calculated location, using the GBM trigger data, is RA = 234.1, DEC = -64.6 (J2000 degrees, equivalent to 15 h 36.5 m, -64 d 36 '), with an uncertainty of 6.9 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 55 degrees.

The GBM light curve consists of a single pulse with a duration (T90) of about 42 s (50-300 keV).  The time-averaged spectrum from T0-18.43 s to T0+18.43 s is best fit by a simple power law function with index -1.51+/- 0.04 (chi squared 233 for 220 d.o.f.).

The event fluence (50-300 keV) in this time interval is (2.45 +/- 0.06)E-6 erg/cm^2. The 6.14-sec peak photon flux measured starting from T0-6.144 s in the 50-300 keV band is 0.60 +/- 0.02 ph/s/cm^2.

The spectral and timing analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."