TITLE:   GCN CIRCULAR
NUMBER:  10333
SUBJECT: GRB 100116A: Fermi LAT detection
DATE:    10/01/17 05:04:12 GMT
FROM:    Julie McEnery at NASA/GSFC  <julie.e.mcenery@nasa.gov>

Julie McEnery (GSFC), Jim Chiang (SLAC), Nicola Omodei (Stanford) and
Tak Nakamori (Tokyo Institute of Technology) report on behalf of the 
Fermi LAT team:

At 21:32:36.00 (UT) on 16 Jan 2010, the Fermi Large Area Telescope
(LAT) detected gamma rays from the long GRB 100116A, which was
triggered and located by the Fermi Gamma-ray Burst Monitor (GBM)
(trigger 285370262 / 100116.897, GCN10330). The angle of the GBM best
position (RA, Dec= 301.48, 16.24) with respect to the LAT boresight was
~29 degrees at the time of the LAT detection, which is well within our
field of view.

The data from the Fermi LAT shows an increase in the event rate coincident
with the second peak in the GBM lightcurve (around 90s after the GBM 
trigger)
that is spatially correlated with the GBM emission. It is a relatively weak
detection with less than 20 excess events, most with energy below 100 MeV.

The best LAT on-ground localization is found to be (RA, Dec = 305.02,
14.45) (RA=20h 20' 04.80'', Dec=14d 27' 00.0'', J2000) with a 90%
containment radius of 0.30 deg (statistical; 68% containment radius: 
0.17 deg)
which is consistent with the GBM localization.

A Swift TOO request cannot be requested due to Sun constraints.

Further analysis is ongoing.

The point of contact for this burst is

Julie McEnery: julie.mcenery@nasa.gov

The Fermi LAT is a pair conversion telescope designed to cover the
energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between NASA and
DOE in the U.S. and many scientific institutions across France, Italy,
Japan and Sweden.

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