{
  "subject": "GRB 241228B: D50 optical detection",
  "eventId": "GRB 241228B",
  "submittedHow": "email",
  "bibcode": "2024GCN.38715....1S",
  "createdOn": 1735511720657,
  "circularId": 38715,
  "submitter": "Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>",
  "body": "J. Strobl and M. Jelinek (ASU CAS Ondrejov) report:\n\nWe observed the position of the Fermi/GBM-detected GRB 241228B (Fermi GBM team, GCN 38682) observed also by Swift/XRT (Evans, GCN 38688) with the D50 telescope of the Astronomical Institute in Ondřejov, near Prague, Czech Republic. Our observation started 16.4 h after the initial trigger and was performed with an SDSS r' filter.\n\nWe detect the optical counterpart (Kumar et al., GCNs 38684 and 38691; An et al., GCN 38687; Ortega-Casas et al., GCN 38692; Ghosh et al., GCN 38702; Xu et al., GCN 38704) in multiple combined 24x120 s frames obtained between 16.4 and 21.9 h after the trigger. Based on our observations, at 18 h after trigger the source had r' = 20.4 +/- 0.1 (AB).\n"
}