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GCN Circular 9021

Subject
Fermi GBM and LAT detections of GRB 090323
Date
2009-03-23T21:24:41Z (15 years ago)
From
Alexander van der Horst at NASA/MSFC <Alexander.J.VanDerHorst@nasa.gov>
Masanori Ohno (ISAS/JAXA), Sara Cutini (ASDC), Julie McEnery (NASA/GSFC),
Jim Chiang (SLAC/KIPAC), Elmar Koerding (AIM/Saclay) report on behalf of
the Fermi LAT team, and Alexander van der Horst (NASA/MSFC/ORAU) reports
on behalf of the Fermi GBM team.

"At 00:02:42.63 UT on 23 March 2009, the Fermi Gamma-Ray Burst Monitor
(GBM) triggered and located GRB 090323 (trigger 259459364 / 090323002).
The GBM light curve consists of multiple peaks and has a duration of
~150 seconds.

The Fermi Large Area Telescope (LAT) has significantly, with more than
5 sigma, detected this GRB. Emission was observed in the LAT up to a few
GeV. The high-energy emission commences several seconds after the GBM
trigger time, and we see marginal evidence in the LAT that it continues
for up to a couple of kilo-seconds.

The best LAT on-ground localization is found to be (RA,Dec=190.69, 17.08)
with a 68% (resp. 90%) containment radius of 0.09 deg (resp. 0.14,
statistical), and a systematic error less than 0.1 deg. The GBM on-ground
localization is consistent with this LAT localization within statistical
and systematic uncertainties.

We further report that the Fermi Observatory executed a maneuver following
this trigger and tracked the burst location for the next 5 hours, subject
to Earth-angle constraints.

Further analysis is ongoing.

The points of contact for this burst are Masanori Ohno (LAT,
ohno@astro.isas.jaxa.jp) and Alexander van der Horst (GBM,
Alexander.J.VanDerHorst@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.

This message can be cited."
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