TITLE: GCN CIRCULAR NUMBER: 42028 SUBJECT: GRB 250929A: Fermi GBM Final Real-time Localization DATE: 25/09/29 20:16:36 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM do_not_reply@GIOC.nsstc.nasa.gov
The Fermi GBM team reports the detection of a likely LONG GRB
At 20:06:07 UT on 29 Sep 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250929A (trigger 780869172.178268 / 250929838).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 58.2, Dec = -60.2 (J2000 degrees, equivalent to J2000 03h 52m, -60d 12'), with a statistical uncertainty of 11.5 degrees.
The angle from the Fermi LAT boresight is 73.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250929838/q...
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250929838/q...
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250929838/q...
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