[vsnet-grb-info 7212] Fermi/GBM detection of GRB 081226A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8785
SUBJECT: Fermi/GBM detection of GRB 081226A
DATE:    09/01/07 16:48:20 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 01:03:37.53 UT on 26 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081226 (trigger 251946218, trigcat 081226044), which was also detected by the SWIFT-BAT (Godet et al. 2008, GCN 8729). The on-ground calculated location, using the GBM trigger data, is RA = 119.01, DEC = -73.8 (J2000 degrees, equivalent to 07 h 56.04 m, -73 d 48'), with an uncertainty of 13.2 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The GBM on-ground location is consistent with the Swift position.
 
The angle from the Fermi LAT boresight is 110 degrees.

The GBM light curve is a single pulse with a duration (T90) of about 1.7 s (20-775 keV). The time-averaged spectrum from T0-0.215 s to T0+0.233 s is best fit by a simple power law function with index 1.17 +/- 0.08 (chi squared 188 for 228 d.o.f.).

The event fluence (50-300 keV) in this time interval is (2.1 +/- 0.1)E-7 erg/cm^2. The 0.256-sec peak photon flux measured starting from T0-0.151 s in the 50-300 keV band is 3.2 +/- 0.1 ph/s/cm^2.

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