[vsnet-grb-info 16157] GRB 150210A: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17438
SUBJECT: GRB 150210A: Fermi-LAT detection
DATE:    15/02/11 14:16:23 GMT
FROM:    Sylvia J. Zhu at NASA/GSFC/UMD  <sjzhu at umd.edu>

S. Zhu (UMD), E. Bissaldi (INFN Bari), J. Racusin (NASA/GSFC),
E. Sonbas (Adiyaman Univ.), D. Kocevski (NASA/GSFC),
M. Yassine (LUPM) report on behalf of the Fermi-LAT team:

At 22:26:24.28 UT on 10 February 2015, Fermi-LAT detected
high-energy emission from GRB 150210A,
which was also detected by Fermi-GBM (trigger 445299987 / 150210935)
(Burns, GCN 17432).

The best LAT on-ground location is found to be

RA, Dec = (112.15, 13.27) (J2000)

with an error radius of 0.33 deg (90% containment, statistical error only).
This position was 55 deg from the LAT boresight at the time of the trigger
and is consistent with the GBM position. It remained in the
LAT field of view for about 1000 seconds after trigger, and reentered
the field of view at T0+5000 seconds.

The data from the Fermi-LAT show a significant increase
in the event rate within 10 degrees of the GBM location after the
GBM trigger that is spatially and temporally correlated
with the GBM emission with high significance.
More than 20 photons above 100 MeV are observed in the first 100
seconds, of which ~15 photons are coincident with the GBM peak.
The highest-energy photon is a  ~1 GeV event which is observed
2 seconds after the GBM trigger. Using the LAT Low Energy (LLE)
data selection, an increase in the event rate at > 20 sigma significance
above background was observed approximately coincident with the
time of the GBM emission.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Sylvia Zhu
(sjzhu at umd.edu).


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.