{
  "bibcode": "2010GCN.11175....1S",
  "body": "D.K. Sahu, B.C. Bhatt, Sonam Arora and Pepsi Anto (IIA, Bangalore) report.\n\nOptical afterglow of GRB 100901A (Immler et al. GCN 11159)\nwas obsrved   with the 2m. Himalayan Chandra Telescope of the\nIndian Astronomical Observatory, Hanle, India. A series of\nexposures were taken in Bessell V, R and I  bands, between\n17:35 UT and 22:15 UT on 01/09/2010. The optical afterglow was\ndetected in all our frames. The preliminary R and I magnitudes\nof the optical afterglow calibrated using  USNO B1.0 1127-0027231\nreference star (R=15.37, I=15.13) is as under:\nMid UT      Exposure     Filter      Mag\n17:42       300sec        R        17.34 +/- 0.05\n19:44       300sec        R        17.03 +/- 0.05\n22:05       300sec        R        17.08 +/- 0.04\n17:51       300sec        I        17.05 +/- 0.05\n19:51       300sec        I        16.76 +/- 0.04\n\nThis message may be cited.",
  "circularId": 11175,
  "createdOn": 1283434474000,
  "email": "dks@iiap.res.in",
  "subject": "GRB 100901A : HCT optical observations",
  "submitter": "D.K. Sahu at Indian Inst of Astrophysics,Bangalore  <dks@iiap.res.in>",
  "eventId": "GRB 100901A"
}