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 33440

GRB 230308A: Fermi GBM detection
2023-03-09T15:35:20Z (a year ago)
Oliver J Roberts at USRA/NASA <>
C. Malacaria (ISSI) reports on behalf of the Fermi GBM Team:

"At 13:32:27.40 UT on 8 March 2023, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 230308A (trigger 699975152 / 230308564).
The Fermi GBM Final Real-time Localization was reported in GCN 33420.

The angle from the Fermi LAT boresight at the GBM trigger time is 42 degrees.

The GBM light curve consists of a slightly structured main peak
with a duration (T90) of about 0.6 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.64 s
is best fit by a power law function with an exponential high-energy cutoff.
The power law index is -0.52 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 943 +/- 46 keV.

A Band function fits the spectrum equally well
with Epeak= 907 +/- 52 keV, alpha = -0.51 +/- 0.03,
beta = -3.1 +/- 0.4 .

The event fluence (10-1000 keV) in this time interval is
(8.5 +/- 0.2)E-06  erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0 in the 10-1000 keV band
is 72 +/- 2 ph/s/cm^2.

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

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:"
Looking for U.S. government information and services? Visit