GCN Circular 8877
Subject
GRB 090202: Fermi GBM detection
Date
2009-02-03T10:14:37Z (16 years ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:
"At 08:19:30.40 UT on 02 February 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090202 (trigger 255255572 / 090202347).
The on-ground calculated location, using the GBM trigger
data, is RA = 268.9, DEC = -2.5 (J2000 degrees,
equivalent to 17h 56m, -02d 30'), with an uncertainty
of 2.3 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.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve shows a single peak and a tail
with a duration (T90) of about 66 s (8-1000 keV).
The time-averaged spectrum from T0-1.536 s to T0+15.872 s is
best fit by a power law function with an exponential
high energy cutoff. The power law index is -1.31 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 570 +/- 170 keV
(chi squared 510.50 for 485 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(8.65 +/- 0.31)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.704 s in the 8-1000 keV band
is 7.77 +/- 0.41 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."