{
  "bibcode": "2012GCN.13797....1Z",
  "body": "W. Zheng (U Mich) and T. Guver (Sabanci U) report on behalf of the ROTSE\ncollaboration: \n\nROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 120923A\n(Swift trigger 534402; Yershov et al., GCN 13796), producing images\nbeginning 0.7 s after the GCN notice time. An automated response took the\nfirst image at 05:17:43.7 UT, 97.4 s after the burst, under fair conditions.\nWe took 10 5-sec, 10 20-sec and 0 60-sec exposures. These unfiltered images\nare calibrated relative to USNO A2.0 (R). Imaging is on going. \n\nComparison to the DSS (second epoch) reveals no new sources within the\n3-sigma Swift/BAT error circle. Individual images have limiting magnitudes\nranging from 15.4-16.3; we set the following specific limits. \n\nstart UT       end UT      t_exp(s)   mlim     Coadd?\n\n------------------------------------------------------\n\n05:17:43     05:17:48           5      15.6        N\n\n05:17:55     05:18:00           5      15.4        N\n\n05:18:07     05:18:12           5      15.7        N\n\n05:17:43     05:19:31           50     16.4        Y",
  "circularId": 13797,
  "createdOn": 1348378898000,
  "email": "zwk@umich.edu",
  "subject": "GRB 120923A: ROTSE-III Optical Limits",
  "submitter": "Weikang Zheng at U.of Michigan  <zwk@umich.edu>",
  "eventId": "GRB 120923A"
}