GCN Circular 30229

A. S. Moskvitin and O. A. Maslennikova (SAO RAS),
report on behalf of the GRB follow-up team.

We observed the field of the GRB 210610A (Page et al., GCN #30160)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer in Rc band
on June 11 and 12.

We clearly detected the GRB OT (Page et al., GCN #30160;
Hosokawa et al., GCNs #30161, #30169; Xu et al., GCN #30162;
Kumar et al., GCN #30163; Zhu et al., GCN # 30164; Lipunov et al.,
GCN #30166; de Wet et al., GCN #30168; Horiuchi et al., GCN #30169;
Sun et al., GCN #30185; Watson et al., GCN #30191; Dutta et al.,
GCN #30200; Zheng et al., GCN #30203, Kann et al., GCN #30211;
Belkin et al., GCN #30214) in the stacked frame obtained
on June 11 and marginally detected the object in the stacked frame
obtained on June 12.

Date      UT_start  UT_end    Exp., s   T_mid-T0, d   R mag
June, 11  20:12:02--21:08:03   8 x 300  1.23356       22.43 +/- 0.14
June, 12  19:46:09--21:08:36  12 x 300  2.22477       23.3  +/- 0.3

The preliminary photometry is based on magnitudes of the nearby
SDSS stars (transformed with the Lupton 2005 equations).
The OT magnitudes were not corrected for MW extinction.