{
  "bibcode": "2015GCN.18435....1Y",
  "body": "K. Yanagisawa, D. Kuroda, Y. Shimizu, H. Izumiura(OAO/NAOJ),\nM. Yoshida (Hiroshima), K. Ohta(Kyoto) and N. Kawai(Tokyo Tech.)\nreport on behalf of the MITSuME collaboration:\n\nWe observed the field of GRB 151021A (Melandri et al., GCN 18425)\nin Ks-band with a wide-field near infrared imager at Okayama\nAstrophysical Observatory (Japan).  The imager has effective\naperture of 0.91 m.\n\nObservations started from 10:42 UT on 21th October, 9.2h after\nthe BAT trigger, to 11:11 UT. The total exposure of 11.7 min\nwas successfully obtained.\n\nIn our co-add image, we did not find any new point source within\nthe enhanced XRT error circle (Osborne et al., GCN 18428) down\nto limiting magnitude of Ks=14.5 (Vega, S/N=10). The photometric\ncalibration was made against 2MASS field stars.\n\nT0+[sec]    MID-UT     T-EXP[sec]      Ks\n---------------------------------------------------\n +34,049    10:56      700.0           >14.5\n---------------------------------------------------\nT0+ : Elapsed time after the burt [sec]\nT-EXP: Total Exposure time [sec]",
  "circularId": 18435,
  "createdOn": 1445494791000,
  "email": "yanagi@oao.nao.ac.jp",
  "subject": "GRB 151021A: MITSuME Okayama Ks-band upper-limit",
  "submitter": "Kenshi Yanagisawa at OAO/NAOJ  <yanagi@oao.nao.ac.jp>",
  "eventId": "GRB 151021A"
}