//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29896 SUBJECT: GRB 210424A: Fermi GBM Final Real-time Localization DATE: 21/04/24 18:50:18 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 18:40:11 UT on 24 Apr 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210424A (trigger 640982416.446996 / 210424778). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 9.0, Dec = 13.7 (J2000 degrees, equivalent to J2000 00h 36m, 13d 41'), with a statistical uncertainty of 14.1 degrees. The angle from the Fermi LAT boresight is 72.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210424778/quicklook/glg_skymap_all_bn210424778.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/bn210424778/quicklook/glg_healpix_all_bn210424778.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210424778/quicklook/glg_lc_medres34_bn210424778.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29898 SUBJECT: GRB 210424.694: DDOTI Upper Limits on the Afterglow DATE: 21/04/25 14:46:28 GMT FROM: Alan M Watson at UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara (GSFC/UMD), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl Lopez (UNAM), Diego Gonzalez (UNAM), Margarita Pereyra (UNAM), Srihari Ravi (ASU), and Eleonora Troja (GSFC/UMD) report: We observed the field of the Fermi/GBM GRB 210424.694 (trigger 640975205) with the DDOTI wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from 2021-04-25 03:39 to 11:50 UTC (from 11.0 to 19.2 hours after the trigger). We observed a region covering aproximately 20 degrees in RA and 20 degrees in declination (6 instrumental fields or about 400 square degrees) centered on the final GBM position and obtained 3420 to 3600 seconds of exposure per instrumental field in the w filter. We obtained AB photometry by calibration against the APASS catalog. We detect no likely candidate for the afterglow to our 10-sigma upper limits of w = 19.15 to 19.55 (interquartile range). We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir.