GCN Circular 39623
Subject
GRB 250309A: Fermi GBM Final Real-time Localization
Date
2025-03-09T00:53:02Z (a month ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely SHORT GRB
At 00:42:03 UT on 9 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250309A (trigger 763173728.785018 / 250309029).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 46.7, Dec = 58.0 (J2000 degrees, equivalent to J2000 03h 06m, 58d 00'), with a statistical uncertainty of 22.9 degrees.
The angle from the Fermi LAT boresight is 22.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250309029/quicklook/glg_skymap_all_bn250309029.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250309029/quicklook/glg_healpix_all_bn250309029.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250309029/quicklook/glg_lc_medres34_bn250309029.gif