GCN Circular 10448

Colleen Wilson-Hodge (NASA) and Sylvain Guiriec (UAH)
report on behalf of the Fermi GBM Team:

"At 02:38:09.31 UT on 23 February 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100223A (trigger 288585491 / 100223110).

The on-ground calculated location, using the GBM trigger
data, is RA = 104.1, DEC = +2.8 (J2000 degrees,
equivalent to 6 h 56 m, 2 d 48 '), with an uncertainty
of 3.6 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 76 degrees.

GBM triggered on a soft peak lasting about 0.05 s followed few ms later by
a longer and harder one. The T90 duration is about 0.206 s (50-300 keV).
The time-averaged spectrum from T0-0.01 s to T0+0.22 s is
adequately fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.31 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 1143 +/- 109 keV
(Castor C-stat 570.83 for 605 d.o.f.).

The event fluence (10-1000 keV) in this time interval is
(1.42 +/- 0.04)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.01 s in the 10-1000 keV band
is 12.5 +/- 0.4 ph/s/cm^2.

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