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GCN Circular 34387

Subject
GRB 230812B: Fermi GBM detection of an extremely bright GRB
Date
2023-08-12T19:51:19Z (4 months ago)
From
Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>
Via
Web form
S. Lesage (UAH), E. Burns (LSU), S. Dalessi (UAH), and O. Roberts (USRA)
report on behalf of the Fermi GBM Team:

"At 18:58:12 UT on 12 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230812B (trigger 713559497/230812790).

The GBM light curve consists of an extremely bright short pulse, with the bulk of the emission during the first 2 seconds, and continued emission out to roughly 20 seconds. This event, if it is a GRB, it is extremely bright and follow-up across all wavelengths is encouraged.

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 250.06, Dec = 46.20 (J2000 degrees, equivalent to J2000 16h 40m, +46d 12'), with a statistical uncertainty of 1.00 degree
(radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight is 29 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_skymap_all_bn230812790.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_healpix_all_bn230812790.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/quicklook/glg_lc_medres34_bn230812790.gif"
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