[vsnet-grb-info 20180] GRB 171222A: Nanshan-0.36m optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22276
SUBJECT: GRB 171222A: Nanshan-0.36m optical upper limit
DATE:    17/12/23 14:34:17 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu at nao.cas.cn>

H.J. Tan (CCU), H.X. Feng, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 
Senior High School) report

We observed the field of GRB 171222A (Racusin et al., GCN 22265) using 
the 0.36m robotic telescope located at Nanshan, Xinjiang, China. 
Observations started at 17:04:17 UT on 2017-12-22, i.e., 39.3 mins after 
the BAT trigger, and all imaged were taken without filter.

No optical source is detected at the XRT position (Osborne et al., GCN 
22266) as well as the NOT position (Perley et al., GCN 22269), down to a 
limiting magnitude of m(R)~19.3, calibrated with the USNO B1 field.