{
  "bibcode": "2022GCN.32811....1G",
  "body": "Rahul Gupta, Amit Kumar Ror, S. B. Pandey, A. Aryan, A. Ghosh, Dimple, and\nK. Misra (ARIES) report as a part of a larger international collaboration:\n\n\nWe performed target of opportunity observations of the extremely bright GRB\n221009A (Dichiara et al., GCN 32632; Kennea and Williams, GCN 32635; Veres\net al., GCN 32636; Bissaldi et al., GCN 32637; Svinkin et al., GCN 32641; Ursi\net al., GCN 32650; Piano et al., GCN 32657; Pillera et al., GCN 32658; Gotz\net al., GCN 32660; Xiao et al., GCN 32661; Frederiks et al., GCN 32668; Ripa\net al., GCN 32685) using the 2Kx2K CCD Imager mounted at the 1.3m Devasthal\nFast Optical Telescope (DFOT) located at the Devasthal observatory of\nAryabhatta Research Institute of Observational Sciences (ARIES), India. The\nobservations were started on 2022-10-16 at 14:41:41 UT, i.e., ~ 7.06 days\nafter the detection. We have taken multiple frames in the R filter at\ndifferent epochs. We clearly detected the optical afterglow of GRB\n221009A (GCNs\n32632, 32635, 32636, 32641, 32657, 32658, 32660, 32666, 32668, 32670,\n32671, 32676, 32677, 32678, 32679, 32680, 32683, 32684, 32685, 32686,\n32691, 32692, 32693, 32694, 32695, 32700, 32705, 32707, 32709, 32727,\n32729, 32730, 32736, 32738, 32739, 32740, 32743, 32746, 32749, 32750;\n32752; 32753; 32755; 32758; 32765; 32769; 32771; 32795; 32799; 32800;\n32803; 32804; 32809) in our stacked image. The preliminary photometric\nestimate of the afterglow is the following :\n\nDate Start UT   T-T0 (mid, days) Filter  Exp time (sec)   Magnitude\n\n=========================================================\n2022-10-16 14:41:41   ~7.09       R           200*25          21.30 +/- 0.04\n\n\nFurther follow-up observations are planned. The magnitude is not corrected\nfor the Galactic extinction in the direction of the burst. Photometric\ncalibration is performed using the standard stars from the USNO-B1.0\ncatalog.\n\nThis circular may be cited.",
  "circularId": 32811,
  "createdOn": 1666336284000,
  "email": "rahulbhu.c157@gmail.com",
  "subject": "GRB 221009A: 1.3m DFOT Optical Observations",
  "submitter": "Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>",
  "eventId": "GRB 221009A"
}