TITLE:   GCN CIRCULAR
NUMBER:  30343
SUBJECT: GRB 210619B: Sayan observatory 1.6-m telescope observations
DATE:    21/06/29 20:14:37 GMT
FROM:    Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>

I. Zaznobin, R. Burenin, A. Lutovinov (IKI),
E. Klunko, M. Eselevich (ISTP SB RAS)

report:

The field of GRB 210619B detected by Swift (D'Avanzo et al. GCN
30261), GECAM (Zhao et al. GCN 30264), CALET (Kawakubo et al. GCNC
30284), SRG/ART-XC (Levin et al. GCNC 30283), Fermi-LAT (Axelsson et
al. GCNC 30270), Konus-Wind (Svinkin et al. GCN 30276) and Fermi/GBM
(Poolakkil et al. GCNC 30279) was observed with the Sayan observatory
1.6-m telescope AZT-33IK, using a CCD photometer, starting at
2021/06/20 17:58 UT, i.e. approximately 18 hours after the burst.

We obtained 12x60 s images in each g,r,i,z SDSS filter. The OT is
clearly detected in every frame, with the following magnitudes:

g = 20.26 +- 0.06
r = 19.51 +- 0.08
i = 19.08 +- 0.06
z = 18.69 +- 0.07