{
  "bibcode": "2018GCN.23590....1O",
  "body": "M. Oeda, K. L. Murata, R. Itoh, Y. Tachibana, S. Harita, K. Morita, K.\nShiraishi, K. Iida, M. Niwano, R. Adachi, Y. Yatsu, and N. Kawai (Tokyo\nTech)\nreport on behalf of the MITSuME collaboration:\n\nWe searched for the optical counterpart of GRB 181228A (M. J. Moss  et al.,\nGCN Circular #23570) with the optical three color (g', Rc, and Ic) CCD\ncameras attached to the MITSuME 50 cm telescope of Akeno Observatory,\nYamanashi, Japan.\n\nThe observation started on 09:04:35.19 UT. We did not find any new point\nsource within the enhanced XRT circle (A.P. Beardmore et al., GCN Circular\n#23574) in all three bands. We obtained following limits for the magnitudes.\n\nT0+[hour]    MID-UT      T-EXP[sec]    g'       Rc        Ic\n-------------------------------------------------------------------------------------------------------\n6.188       13:04:51          25320      >19.1     >19.0     >18.6\n-------------------------------------------------------------------------------------------------------\nT0+ : Elapsed time after the burst\nT-EXP: Total Exposure time\nWe used UCAC-4 catalog for flux calibration.",
  "circularId": 23590,
  "createdOn": 1546172553000,
  "email": "murata@u.phys.nagoya-u.ac.jp",
  "subject": "GRB 181228A: MITSuME Akeno optical upper limits",
  "submitter": "Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>",
  "eventId": "GRB 181228A"
}