[vsnet-grb-info 27132] GRB 210104A: GWAC-F60A optical afterglow observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29235
SUBJECT: GRB 210104A:  GWAC-F60A optical afterglow observations
DATE:    21/01/04 12:00:26 GMT
FROM:    Liping Xin at NAOC, SVOM  <xlp at nao.cas.cn>

L. P. Xin(NAOC),  J. Wang(GXU), X. H. Han(NAOC), J. Y. Wei(NAOC), 
G. W. LI(NAOC),  L. H. Li(NAOC), C. Wu(NAOC),  X. G. Wang(GXU), 
E. W. Liang (GXU), R. S. Zhang(NAOC), Y. L. Qiu(NAOC), 
and J. S. Deng(NAOC) report: 

We began to observe GRB 210104A (Troja et al., GCN 29233)
with Xinglong GWAC-F60A telescope, China, 
at 11:28:00 (UT), 4th. Jan. 2021, about 61 sec after the burst.

A series of  R, I, and B band images were obtained.
The optical afterglow (Troja et al., GCN 29233) 
was clear detected in our images. 

The brightness is about 14.5 mag in R band at 71 sec after the burst,
calibrated to the USNO B1.0 catalog.

The observations are continuing