GCN Circular 9040
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 09:41:41.51 UT on 27 March 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090327 (trigger 259839703 / 090327404). The on-ground calculated location, using the GBM trigger data, is RA = 29.5, DEC = -41.6 (J2000 degrees, equivalent to 01h 58m, -41d 36'), with an uncertainty of 3.4 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 66 degrees. The GBM light curve consists of single peak with a duration (T90) of about 24 s (8-1000 keV). The time-averaged spectrum from T0 to T0+16.384 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.50 +/- 0.12 and the cutoff energy, parameterized as Epeak, is 96.4 +/- 5.1 keV (chi squared 550 for 475 d.o.f.). The event fluence (8-1000 keV) in this time interval is (3.0 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+9.216 s in the 8-1000 keV band is 3.5 +/- 0.7 ph/s/cm^2. A Band function fits the spectrum equally well (chi squared 549 for 474 d.o.f.) with Epeak= 89.7 +/- 7.0 keV, alpha = -0.39 +/- 0.16 and beta = -2.90 +/- 0.45. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."