{
  "bibcode": "2021GCN.30982....1K",
  "body": "D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/DARK/NBI), C. C. \nThoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), \nIglesias-Marzoa, R., and Lacruz, E. (both OAJ) report:\n\nWe observed the Fermi-LAT position (Di Lalla et al., GCN #30961) of the \nbright Fermi GRB 211023A (Fermi detection: Fermi GBM Team, GCN #30958; \nLesage et al., GCN #30965; AGILE detection: Ursi et al., GCN #30969) \nwith the JAST/T80 telescope of OAJ, Teruel, Spain. We obtained 3 x 300 s \nimages each in g', r', and i' under good conditions.\n\nAt the position of the MASTER afterglow candidate (Zhirkov et al., GCN \n#30977), we detect a bright source which is not visible in Pan-STARRS \narchival imaging. Against three Pan-STARRS comparison stars, we measure \nr' = 18.03 +/- 0.02 mag (AB mag) at 0.5704 d after the GRB.\n\nWe note this is an exceedingly bright afterglow, just slightly fainter \nat similar times than those of GRBs 130427A and 181201A. We also note a \nresemblance in prompt emission shape, fluence (S. Poolakkil, priv. \ncomm.), and peak energy to the famous GRB 030329. Spectroscopic \nobservations and further follow-up are encouraged.",
  "circularId": 30982,
  "createdOn": 1635122745000,
  "email": "kann@iaa.es",
  "subject": "GRB 211023A: OAJ Bright Afterglow Confirmation",
  "submitter": "Alexander Kann at IAA-CSIC  <kann@iaa.es>",
  "eventId": "GRB 211023A"
}