{
  "bibcode": "2021GCN.31028....1J",
  "body": "M. Jelinek, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov)\nreport:\n\nWe observed the position of the very long GRB 211024B (Gropp et al., GCN\n30980, Lien et al. GCN 30989 and Evans et al. GCN 30994) with the D50\ntelescope of the Astronomical Institute Ondrejov, near Prague, Czech\nRepublic. We obtained a set of 175x 60s exposures in Sloan i' filter as\nsoon as the position became accessible above the local horizon, between\n3.16 and 6.35h after the trigger.\n\nThe optical afterglow (Lipunov et al., GCN 30981; Zhu et al., GCN 30984;\nKann et al., GCN 30995; Kuin et al., GCN 31005) is clearly detected in\nweight-combined images. In particular, we measure i'=19.94+/-0.11 in a\n38x60s frame with an exposure mid time T0+0.152d. The calibration was done\nagainst Atlas stars in the field.",
  "circularId": 31028,
  "createdOn": 1635801129000,
  "email": "martin.jelinek@asu.cas.cz",
  "subject": "GRB 211024B: Optical afterglow observation by Ondrejov D50",
  "submitter": "Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>",
  "eventId": "GRB 211024B"
}