TITLE:   GCN CIRCULAR
NUMBER:  30162
SUBJECT: GRB 210610A: Xinglong-2.16m optical afterglow observations
DATE:    21/06/10 16:20:29 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu, Z.P. Zhu, S.Y. Fu, X. Liu (NAOC) report on behalf of a larger 
collaboration:

We observed the field of GRB 210610A (Page et al., GCN 30160) using the 
2.16-m optical telescope located at Xinglong, Hebei, China, equipped 
with the BFOSC camera. Observations started at 15:28:02 UT on 
2021-06-10, i.e., 24.25 min after the burst.

An uncatalogued and varying optical transient is detected at coordinates:

R.A. (J2000) = 13:37:07.60
Dec. (J2000) = +14:27:55.0

with an error radius of ~ 0.3 arsec, positionally being well consistent 
with the Swift/UVOT detection (Page et al., GCN 30160). The OT is thus 
the optical afterglow of the GRB, and it has r = 16.97 +/- 0.01 mag at 
26.25 min post-burst, calibrated with the nearby PanSTAR field.

Spectroscopy of the afterglow is underway.