TITLE:   GCN CIRCULAR
NUMBER:  30291
SUBJECT: GRB 210619B: SAO RAS optical observations
DATE:    21/06/21 13:32:22 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

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

We observed the field of Swift GRB 210619B (D'Avanzo et al.,
GCNs #30261, #30288, #30289; Jelinek et al., GCNs #30263, #30281;
Lipunov et al., GCN #30259; Zhao et al., GCN #30261; Kong et al.,
GCN #30265; Axelsson et al., #GCN 30270; de Ugarte Postigo et al.,
GCN #30272; Zheng et al., GCN #30273; Blazek et al., GCN #30274;
Kann et al., GCN #30275; Svinkin et al., GCN #30276; Xin et al.,
GCN $30277; Perley et al., GCN #30271, Shrestha et al., GCN #30280,
Kumar et al. GCN #30286; Cunningham et al., GCN #30290)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer.
We obtained 6 x 300 sec. frames in Rc band on June 20/21
(23:31:43--00:03:05 UT), T_mid-T0 = 0.99166d.

The OT is clearly detected in the stacked frame with the brightness
R = 19.8 +/- 0.1 (based on nearby USNO-B1 stars).