GCN Circular 8977
Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "At 04:32:49.90 UT on 10 March 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090310 (trigger 258352371 / 090310189). The on-ground calculated location, using the GBM trigger data, is RA = 181.9, DEC = -38.7 (J2000 degrees, equivalent to 12 h 07 m, -38 d 42 '), with an uncertainty of 5.7 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 77 degrees. The GBM light curve shows one bright, narrow peak lasting about 4s followed by several fainter peaks with a total duration (T90) of about 125.2 s (8-1000 keV). The time-averaged spectrum from T0-0.128 s to T0+3.968 s is well fit by a power law function with an exponential high-energy cutoff at 279 +/- 43 keV and with index -0.65 +/- 0.13 (chi squared 504 for 536 d.o.f.). The event fluence (8-1000 keV) in this time interval is (2.15 +/- 0.17)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.128 s in the 8-1000 keV band is 4.4 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog. This burst was also independently detected, although untriggered, by INTEGRAL SPI-ACS."