TITLE:   GCN CIRCULAR
NUMBER:  30705
SUBJECT: GRB 210824A: Nanshan/NEXT optical upper limit
DATE:    21/08/24 16:06:10 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

X. Liu, S.Y. Fu (NAOC), Z.P. Zhu (NAOC,HUST), D. Xu (NAOC), X. Gao 
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of Swift GRB 210824A (Page et al. GCN Circ. 30700) 
using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We 
obtained 10x200 s frames in the Sloan r-band, starting at 14:54:25 UT on 
2021-08-24, i.e., 10.74 hr after the BAT trigger.

No optical source is detected in our stacked image at the enhanced 
Swift/XRT position (Goad et al., GCN 30702), down to a limiting 
magnitude of r~21.1, calibrated with the nearby PanSTARRS field.