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GCN Circular 10355

Subject
GRB 100122A: Fermi GBM detection
Date
2010-01-23T02:32:50Z (14 years ago)
From
Narayana Bhat at U Alabama/Huntsville/GBM <Narayana.Bhat@nasa.gov>
A. von Kienlin (MPE), P. N. Bhat (UAH) and R. D. Preece (UAH)
report on behalf of the Fermi GBM Team:

"At 14:47:37.31 UT on 22 January 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100122A (trigger 285864459 / 100122616).

The on-ground calculated location, using the GBM trigger
data, is RA = 79.2 , DEC = -2.7 (J2000 degrees,
equivalent to 05h 16.8m, -2d 42'), with an uncertainty
of 1.3 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 45 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.


The GBM light curve consists of 2 pulses (a weak pulse at trigger followed
by a much larger pulse about 21 s later) with a duration (T90)
of about 6.6 s (8-1000 keV).
The time-averaged spectrum from T0-2.688 s to T0+25.984 s is
adequately fit by a Band function with Epeak = 45.6 +/- 1.5 keV,
alpha = -0.98 +/- 0.05, and beta = -2.31 +/- 0.03

(CSTAT 1673 for 478 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.00 +/- 0.01)E-05 erg/cm^2. The 1.0-sec peak photon flux measured
starting from T0+20.9 s in the 8-1000 keV band
is 10.44 +/- 0.07 ph/s/cm^2.

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