{
  "bibcode": "2022GCN.32729....1Z",
  "body": "I. Zaznobin, R. Burenin (IKI), M. Eselevich (ISTP SB RAS)\n\nreport:\n\nThe field of an extraordinarily bright GRB 221009A, detected by Swift\n(Kennea et al., GCN 32635), Fermi GBM (Veres et al., GCN 32636),\nSRG/ART-XC (Lapshov, et al., GCN 32663), Konus-Wind (Frederiks et al.,\nGCN 32668), and others, was observed with the Sayan observatory\n(Mondy) 1.6-m telescope AZT-33IK, using a CCD photometer, starting at\n2022/10/10 13:38 UT, i.e. approximately 24.4 hours after the burst.\n\nThe optical transient found earlier (Dichiara et al., GCN 32632,\nLipunov et al., GCN 32634, Perley et al., GCN 32638, Belkin et al.,\nGCN 32645, and others), was observed in griz filters with the\nfollowing magnitudes:\n\ng = 20.57 +- 0.08\nr = 18.84 +- 0.02\ni = 17.80 +- 0.02\nz = 16.99 +- 0.02\n\nThe decay in OT brigtness in all filters is observed during\napproximately 2 hours of our observations.\n\nSpectra of the OT in 3700--10000A wavelength range were also obtained\nusing ADAM low and medium resolution spectrograph. The analysis of\nthese data is underway.",
  "circularId": 32729,
  "createdOn": 1665644902000,
  "email": "rodion@hea.iki.rssi.ru",
  "subject": "GRB 221009A: Sayan observatory 1.6-m telescope observations",
  "submitter": "Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>",
  "eventId": "GRB 221009A"
}