[vsnet-grb-info 11830] GRB 120404A : TNT optical observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13221
SUBJECT: GRB 120404A : TNT optical observation 
DATE:    12/04/05 00:44:27 GMT
FROM:    L.P. Xin at NAOC  <xlp at bao.ac.cn>

L.P. Xin, J. Y.Wei, Y.L. Qiu, J. Wang,  J.S. Deng, 
C. Wu,  X. H. Han on behalf of EAFON report:
 
We began to observe GRB 120404A (Stratta et al., GCN Circ. 13208)
with Xinglong TNT telescope in R-band at 19:33:05(UT),   6.7 hours after 
the burst. The optical counterpart (Stratta et al., GCN Circ. 13208, Guidorzi et al. GCN Circ. 13209) 
was marginal detected with a brightness of 20.3 +/- 0.2 mag 
calibrated to USNO B1.0 R2 mag, at the mean time of 7.4 hours after the burst.

Combined with the report by Guidorzi et al. ( GCN Circ. 13209 ), the brightness of this burst
decayed by 1.5 magnitude in R-band during 4 min and 7.4 hour after the burst,
corresponding to a shallow decay index of about 0.3 during this phase. 
 
Further observations are encouraged. 

This message may be cited.
 
For more information about Xinglong GRBs Follow-up
observations, please visit the website:
http://www.xinglong-naoc.org:8080/grb/index.html
 
We thank Liang Ma for performing these observations.