TITLE: GCN CIRCULAR NUMBER: 30016 SUBJECT: GRB 210515B: Fermi GBM Final Real-time Localization DATE: 21/05/15 15:07:00 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 14:56:46 UT on 15 May 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210515B (trigger 642783411.180128 / 210515623). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 315.2, Dec = 45.7 (J2000 degrees, equivalent to J2000 21h 00m, 45d 42'), with a statistical uncertainty of 1.6 degrees. The angle from the Fermi LAT boresight is 151.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210515623/quicklook/glg_skymap_all_bn210515623.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/bn210515623/quicklook/glg_healpix_all_bn210515623.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210515623/quicklook/glg_lc_medres34_bn210515623.gif