TITLE:   GCN CIRCULAR
NUMBER:  39422
SUBJECT: GRB 250221A: Assy optical observations
DATE:    25/02/22 11:10:50 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>

 N. Pankov (HSE, IKI), V. Kim (FAI), M. Krugov (FAI), Y. Aimuratov (FAI),
A. Volnova(IKI), A. Pozanenko (IKI) report on behalf of IKI GRB FuN:

We observed the optical afterglow (Francile et al., GCN 39395; Watson et
al., GCN 39397; Melandri et al., GCN 39406; Shilling et al., GCN 39409; Guo
et al., GCN 39412; Muenter et al., GCN 39417; Palmerio et al., GCN 39418)
of the Swift GRB 250221A (Caputo et al., GCN 39396) with AZT-20 telescope
of Assy-Turgen observatory starting on 2025-02-21 (UT) 15:25:09.55 in r'
filter.

The afterglow is clearly detected. Preliminary photometry of the OT in the
stacked image is the following

Date UT start t-T0 Exp. Filter OT Err. UL(3sigma)

2025-02-21 15:25:09 0.50385 30x60 r' 20.90 0.05 22.8

The photometry is based on nearby PS1 stars.