{
  "bibcode": "2021GCN.29254....1P",
  "body": "Gregory S.H. Paek (SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Taewoo Kim,\nand Wonseok Kang (DOAO) on behalf of a larger collaboration\n\nWe observed the optical counterpart of GRB 210104A (E. Troja et al.,\nGCN #29233)\nwith the 1-m class telescope in Deokheung Optical Astronomy Observatory\n(DOAO). We calibrated flux with the SDSS catalog and used an AB magnitude\nsystem.\n----------------------------------------------------------\nFilter Date-obs[UT]            Exp.time[s] Mag   Mag Error\n----------------------------------------------------------\nR      2021-01-04T13:37:29.100 300*4       18.34  0.07\nI      2021-01-04T13:42:37.050 300*4       18.04  0.05\n----------------------------------------------------------\nThe magnitudes are not corrected for galactic extinction.",
  "circularId": 29254,
  "createdOn": 1609817497000,
  "email": "shpaek@astro.snu.ac.kr",
  "subject": "GRB 210104A: DOAO optical afterglow observations",
  "submitter": "Gregory SungHak Paek at SNU  <shpaek@astro.snu.ac.kr>",
  "eventId": "GRB 210104A"
}