TITLE: GCN CIRCULAR NUMBER: 29351 SUBJECT: GRB 210123A: Fermi GBM Final Localization DATE: 21/01/25 21:39:52 GMT FROM: Rachel Dunwoody at UCD The Fermi GBM team reports the detection of a likely long GRB. "At 07:19:03.07 UT on 23 January 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210123A (trigger 633079148 / 210123305). This burst was also independently detected by INTEGRAL SPI-ACS and the Insight-HXMT/HE (Xue et al. 2019, GCN 29349) The on-ground calculated location, using the GBM trigger data, is RA = 345.1, DEC = -56.9 (J2000 degrees, equivalent to 23h 00m, -56d 53'), with a statistical uncertainty of 1.1 degrees. The angle from the Fermi LAT boresight is 110 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210123305/quicklook/glg_skymap_all_bn210123305.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210123305/quicklook/glg_healpix_all_bn210123305.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210123305/quicklook/glg_lc_medres34_bn210123305.gif