TITLE: GCN CIRCULAR NUMBER: 29927 SUBJECT: GRB 210503A: Fermi GBM Final Real-time Localization DATE: 21/05/03 19:44:33 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 19:34:09 UT on 3 May 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210503A (trigger 641763254.461374 / 210503815). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 328.9, Dec = 66.0 (J2000 degrees, equivalent to J2000 21h 55m, 66d 00'), with a statistical uncertainty of 5.1 degrees. The angle from the Fermi LAT boresight is 32.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210503815/quicklook/glg_skymap_all_bn210503815.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/bn210503815/quicklook/glg_healpix_all_bn210503815.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210503815/quicklook/glg_lc_medres34_bn210503815.gif