TITLE:   GCN CIRCULAR
NUMBER:  9305
SUBJECT: GRB 090424: YNAO-GMG observations
DATE:    09/04/30 11:10:12 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao@ynao.ac.cn>

J. Mao (YNAO & INAF-OAB), G. Cha and J. Bai (YNAO) report on behalf of the GMG group: 
 
We observed the optical counterpart of GRB 090424 (Cannizzo et al., GCN 9223) using 
one 2.4-m telescope located at Gao-Mei-Gu (GMG) about 40 minutes after the trigger and
obtained the following magnitudes: 
 
Start UT  Exposure Filter  mag   err 
------------------------------------------------- 
14:53:41  10 sec     R    17.51  0.02 
14:56:41  30 sec     B    18.50  0.03   
15:01:22  30 sec     V    18.57  0.02 
15:03:55  20 sec     I    17.68  0.02 
17:26:58  75 sec     R    18.89  0.04 

We continued our observations of GRB 090424 in R band started at 13:42:00 UT on April 
25, 2009. After 20 minutes of exposure time, we obtained the magnitude R=20.59 +/- 
0.07 mag.     
 
All the calibrations were processed by nearby SDSS stars. 
 
The telescope is charged by Yunnan Observatory (YNAO), Chinese Academy of Sciences.   
 
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