{
  "bibcode": "2011GCN.12378....1T",
  "body": "K. Tokoyoda, M. Hayashi, Y. Yatsu, Y. Aoki, K. Kawakami, S. Song,\nR. Usui, and N. Kawai (Tokyo Tech)  report on behalf of the MITSuME\ncollaboration:\n\nWe observed GRB 110921A (W. H. Baumgartner et al, GCN12373)\nwith the optical three color (g, Rc, and Ic) CCD camera attached\nto the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.\nThe follow-up observation was started at 13:53:08, ~108 sec after the\nBAT trigger.\n\nWe did not find optical counterpart in g'-band and R-band\nwithin the enhanced XRT error circle (W. H. Baumgartner et al, GCN12373).\n\nWhile, in I-band, we detected a very faint OT candidate in the error circle\nonly in the earliest data-set (T0+108s ~ T0 + 348s).\nFurther data analysis for the I-band data is now ongoing.\n\nPhotometric results are listed below. We used GSC2.3 catalog for\nflux calibration.\n\nT0+[s]      MID-UT     T-EXP[sec]      g'             Rc           Ic\n---------------------------------------------------------------------------------\n +108     14:07:40         1530           >20.0       >19.5       ---\n---------------------------------------------------------------------------------\nT0+ : Elapsed time after the burst [sec]\nT-EXP: Total Exposure time [sec]",
  "circularId": 12378,
  "createdOn": 1316623134000,
  "email": "yatsu@hp.phys.titech.ac.jp",
  "subject": "GRB 110921A: MITSuME Akeno Optical Observation",
  "submitter": "Yoichi Yatsu at Tokyo Tech.  <yatsu@hp.phys.titech.ac.jp>",
  "eventId": "GRB 110921A"
}