[vsnet-grb-info 27520] GRB 210308A: Nanshan/NEXT optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29623
SUBJECT: GRB 210308A: Nanshan/NEXT optical upper limits
DATE:    21/03/08 16:27:50 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), X. Gao (Urumqi 
No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 210308A (D'Elia et al., GCN 29619) using 
the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. 
Observations started at 14:16:29 UT on 2021-03-08, i.e., 7.67 hr after 
the BAT trigger. We obtained 15x200 s frames in the Sloan r- and i- 
bands, respectively.

The optical afterglow (D'Elia et al., GCN 29619) of the burst is not 
detected in our stacked images, down to limiting magnitudes of r ~ 21.7 
and i ~ 21.3, calibrated with nearby PS1 stars.