TITLE: GCN CIRCULAR NUMBER: 33600 SUBJECT: GRB 230409C: Fermi GBM Final Real-time Localization DATE: 23/04/09 22:38:23 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 22:27:45 UT on 9 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230409C (trigger 702772070.370746 / 230409936). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 195.9, Dec = -53.4 (J2000 degrees, equivalent to J2000 13h 03m, -53d 23'), with a statistical uncertainty of 10.5 degrees. The angle from the Fermi LAT boresight is 86.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230409936/quicklook/glg_skymap_all_bn230409936.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/bn230409936/quicklook/glg_healpix_all_bn230409936.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230409936/quicklook/glg_lc_medres34_bn230409936.gif