[vsnet-grb-info 8242] GRB 090807B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9767
SUBJECT: GRB 090807B: Fermi GBM detection
DATE:    09/08/11 22:36:36 GMT
FROM:    Bill Paciesas at UAH  <bill.paciesas at nasa.gov>

W. Paciesas (UAHuntsville) reporta on behalf of the Fermi GBM Team:

"At 19:57:59.02 UT on 7 August 2009, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 090807B (trigger 271367881 / 090807.832).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 326.9, Dec = +7.2 (J2000 degrees, equivalent to
J2000 21h 48m, +7d 12'), with a statistical uncertainty of 2.6 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 45 degrees.

The GBM light curve consists of a single structured pulse with a duration
of about 3 s (8-1000 keV). The time-averaged spectrum from T0-0.640 to T0+1.408 s
is best fit by a Band function with Epeak = 37 +/- 5 keV,
alpha = -0.6 +/- 0.4, and beta = -2.4 +/- 0.1 (chi^2 387 for 357 d.o.f.).
The fluence (8-1000 keV) in this time interval is (1.02 +/- 0.07)E-06 erg/cm^2.
The 1-sec peak photon flux measured starting from T0-0.512 s in the 8-1000 keV band
is 10.9 +/- 0.5 ph/s/cm^2.

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