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GCN Circular 12767

GRB 111228A: GMG optical observation
2011-12-29T15:16:14Z (13 years ago)
Xiao-hong Zhao at Yunnan Observatory <>
X.-H. Zhao (YNAO), D. Xu (WIS/NAOC), J.-R. Mao (KASI/YNAO), J.-M. Bai
(YNAO) report:

We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) at the
2.4m Gao-Mei-Gu (GMG) telescope equipped with YFOSC. Observations
started at 16:31:38 UT on 2011-12-28  (i.e., 47 mins after the burst) and 
4x600s R-band images were obtained in a seeing of
~3.36". We found the afterglow was decaying. The results are as follows:
mid time (UT)                            magnitude (err)
 2011-12-28 16:36:38                     17.11 (0.01)  
 2011-12-28 17:19:14                    17.42 (0.01)  
 2011-12-28 17:44:57                    17.56 (0.01)  
 2011-12-28 17:56:15                    17.62 (0.01). 

The magnitudes were calibrated with the USNO-B1 #1083-0199833 star (R2 = 17.28 mag; also
used by Klotz et al., GCN 12746; Nascimbeni et al., GCN 12748; Xu et
al., GCN 12750; Hentunen et al., GCN 12754).

Further observations are planned.

We thank the GMG staff, especially Y.-X. Xin, Fen He, and Gui-Hua He for
performing these observations.

[GCN OPS NOTE(29dec11): Per author's request, the affiliation of X-H.Z. 
was changed to Yunnan Observatory.]
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