TITLE:   GCN CIRCULAR
NUMBER:  31134
SUBJECT: GRB 211023A: Xinglong 2.16m optical observations
DATE:    21/11/29 05:33:13 GMT
FROM:    Liping Xin at NAOC, SVOM  <xlp@nao.cas.cn>

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

We observed the field of the GRB 211023A (Fermi GBM team, GCN 30958; Di
Lalla et al., GCN 30961; Lesage et al, GCN 30965; Ursi et al, GCN 30969;
Poolakkil, GCN 30998; Ridnaia et al., GCN 31022 ) 
with 2.16m optical telescope at Xinglong observatory, China. 
Ten images in R band were obtained from 2021-11-12T16:46:10 UT to 
2021-11-12T17:32:18 UT, about 20.16 days after the burst. 
The exposure time for each image was 300 sec. 

The optical counterpart (Lipunov et al., GCN 30970; Zhirkov et al, GCN 30977; 
Kann et al, GCN 30982; Hu et al, GCN 30990; Belkin et al, GCN 31004; Vinko et al, GCN
31008; Belkin et al, GCN 31018; Belkin et al, GCN 31020; Kumar et al,
GCN 31023; Gupta et al., GCN 31041; Strobl et al., GCN 31042; Pozanenko
et al., GCN 31053; Moskvitin et al., GCN 31066, , Belkin et al., GCN 31098) 
was clearly detected in our the stacked image with a brightness of 22.0 magnitude 
in R-band. The photometry was calibrated with several nearby USNO B1.0 catalogs.