TITLE:   GCN CIRCULAR
NUMBER:  30185
SUBJECT: GRB 210610A: 1.5m OSN optical observation
DATE:    21/06/10 23:49:51 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

T.-R. Sun, Y.-D. Hu, A. Sota, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado and E. Fernandez-Garcia (IAA-CSIC), on behalf of a larger collaboration, report:

Following the detection of GRB 210610A by Swift (Page et al. GCNC 30160), images in BVRI bands were obtained at the 1.5m OSN telescope in Granada (Spain) starting after the twilight as soon as it was possible. In the first I-band 90 s exposure image, the optical afterglow with I = 19.85+-0.18 at 21:12 UT (~6.1 hr after trigger) is clearly seen within the enhanced XRT position (Goad et al. GCNC 30165), which also detected by UVOT/Swift (Page et al. GCNC 30160), MITSuME (Hosokawa et al. GCNC 30161 and Horiuchi et al. GCNC 30169), Xinglong (Xu et al. GCNC 30162), MASTER (Lipunov et al. GCNC 30166) and MeerLICHT (de Wet et al. GCNC 30168). Further observations are ongoing.

We thank the staff at OSN for their excellent support.