[vsnet-grb-info 26910] GRB 201209A: Xinglong-2.16m likely optical afterglow detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29013
SUBJECT: GRB 201209A: Xinglong-2.16m likely optical afterglow detection
DATE:    20/12/09 15:24:53 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu at nao.cas.cn>

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

We observed the field of GRB 201209A (Gropp et al., GCN 29005) using the 
2.16-m optical telescope located at Xinglong, Hebei, China, equipped 
with the BFOSC camera. Observations started at 13:05:43 UT on 
2020-12-09, and 2x360 s, 3x600 s R-band frames were obtained.

An uncatalogued source is detected in our stacked image at coordinates

R.A. (J2000) = 1:32:21.76
Dec. (J2000) = -1:45:17.13

with an uncertainty of ~0.5 arcsec, being fully consistent with the 
Enhanced XRT position (Goad et al., GCN 29009). Calibrated with nearby 
PS1 stars, the source has m(R) = 22.05 +/- 0.16 mag at a median time of 
0.321 days post-burst, whereas PS1 is deeper but no object is present at 
the position. We thus conclude that the source is likely the optical 
afterglow of the burst.

We acknowledge excellent support from the Xinglong-2.16m observing 
staff, in particular Aiying Zhou and Jie Zheng.