TITLE:   GCN CIRCULAR
NUMBER:  29607
SUBJECT: GRB 210306A: NEXT optical observations
DATE:    21/03/07 04:10:04 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@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 210306A (D'Elia et al., GCN 29597) using 
the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. 
Observations started at 16:11:33 UT on 2021-03-06, i.e., 12.29 hr after 
the BAT trigger. We obtained 15x200 s frames in the Sloan r-filter.

The previously reported optical afterglow (e.g., D'Elia et al., GCN 
29597; Watson et al., GCN 29598; Romanov F., GCN 29599; Strausbaugh et 
al., GCN 29600; Hentunen et al., GCN 29603; Stecklum et al., GCN 29604) 
is clearly detected in our stacked image, with r = 21.0 +/- 0.1 mag at 
12.76 hr post-burst, calibrated with nearby PS1 stars.