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GCN Circular 8977

GRB090310: Fermi GBM detection
2009-03-11T16:34:02Z (15 years ago)
Arne Rau at MPE <>
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 
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