{
  "bibcode": "2009GCN..9218....1Y",
  "body": "M. Yoshida, K. Yanagisawa, D. Kuroda, Y. Shimizu, S. Nagayama,\nH. Toda (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf\nof the MITSuME collaboration:\n\nWe observed the field of GRB 090423 (Krimm et al. GCN 9198) with a\nnear-infrared camera ISLE attached to the 188cm telescope of Okayama\nAstrophysical Observatory. We also obtained optical data using the\noptical three color CCD camera attached to the MITSuME 50cm\ntelescope.\n\nWe started the observation at 2009-04-23 10:32:27 UT, 2hr 37m after\nthe burst. We detected a very faint source close to the position of\nthe afterglow candidate reported by Tanvir et al. (GCN 9202) in our\nJ band image. The coordinate of the source is\n    J2000.0   9h 55m 33.3s  +18d 08m 57.1s .\nJ band magnitude of the source is 20.1 mag, which is much fainter\nthan the previous report (Cucchiara et al. GCN 9213).\n\nWe could not find any new source in the optical bands and the other\nnear-infrared bands (H and Ks). The results of our photometry are\nlisted below. We used three 2MASS stars near the burst for near-\ninfrared flux calibration and GSC2.3 catalog for optical flux\ncalibration.\n\n\nNear-infrared observation\nBand    Mid-UT     Td(day)      EXP-T      mag\n------------------------------------------------------\nJ       10:53:33   0.12377      720s    20.1 \u001b$B!^\u001b(B 0.3\nH       11:04:30   0.13138      960s    > 19.3\nKs      10:56:31   0.12584      480s    > 18.7\n------------------------------------------------------\n\n\nOptical observation\n Mid-UT     Td(day)        EXP-T        g'     Rc     Ic\n------------------------------------------------------------\n11:43:56    0.15876        5940s     >20.4   >20.2  >19.5\n------------------------------------------------------------",
  "circularId": 9218,
  "createdOn": 1240545814000,
  "email": "yoshida@oao.nao.ac.jp",
  "subject": "GRB 090423: Near infrared observation at Okayama Observatory",
  "submitter": "Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida@oao.nao.ac.jp>",
  "eventId": "GRB 090423"
}