Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 13339

GRB 120521B: Fermi GBM observation
2012-05-23T09:16:58Z (12 years ago)
David Gruber at MPE <>
David Gruber (MPE) reports on behalf of the Fermi GBM Team:

"At 09:07:52.39 UT on 21 May 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120521B (trigger 359284074 / 120521380).
which was also detected by the Swift/BAT
(Krimm et al. 2012, GCN 13317)
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 84 degrees.

The GBM light curve consists of a single pulse
with a duration (T90) of about 91 s (50-300 keV).
The time-averaged spectrum from T0-5 s to T0+29 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.34 +/- 0.20 and
the cutoff energy, parameterized as Epeak, is 213 +/- 29 keV

The event fluence (10-1000 keV) over the T90 time interval is
(3.11 +/- 0.07)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.4 s in the 10-1000 keV band
is 1.55 +/- 0.23 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
Looking for U.S. government information and services? Visit