{
  "bibcode": "2009GCN..9305....1M",
  "body": "J. Mao (YNAO & INAF-OAB), G. Cha and J. Bai (YNAO) report on behalf of the GMG group: \n \nWe observed the optical counterpart of GRB 090424 (Cannizzo et al., GCN 9223) using \none 2.4-m telescope located at Gao-Mei-Gu (GMG) about 40 minutes after the trigger and\nobtained the following magnitudes: \n \nStart UT  Exposure Filter  mag   err \n------------------------------------------------- \n14:53:41  10 sec     R    17.51  0.02 \n14:56:41  30 sec     B    18.50  0.03   \n15:01:22  30 sec     V    18.57  0.02 \n15:03:55  20 sec     I    17.68  0.02 \n17:26:58  75 sec     R    18.89  0.04 \n\nWe continued our observations of GRB 090424 in R band started at 13:42:00 UT on April \n25, 2009. After 20 minutes of exposure time, we obtained the magnitude R=20.59 +/- \n0.07 mag.     \n \nAll the calibrations were processed by nearby SDSS stars. \n \nThe telescope is charged by Yunnan Observatory (YNAO), Chinese Academy of Sciences.   \n \nThis message might be cited.",
  "circularId": 9305,
  "createdOn": 1241089812000,
  "email": "jirongmao@ynao.ac.cn",
  "subject": "GRB 090424: YNAO-GMG observations",
  "submitter": "Jirong Mao at Yunnan Obs  <jirongmao@ynao.ac.cn>",
  "eventId": "GRB 090424"
}