TITLE:   GCN CIRCULAR
NUMBER:  32088
SUBJECT: GRB 220521A: Sintesz-Newton/CrAO optical upper limit
DATE:    22/05/22 15:17:22 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Nazarov (CrAO), A. Pozanenko (IKI), S. Belkin (IKI, HSE), N. Pankov 
(HSE)  report on behalf of IKI GRB FuN:

We observed  the GRB 220521A (Dichiara et al., GCN 32076; Fermi GBM 
Team, GCN 32075) with Sintesz-Newton 350mm f/5 telescope of CrAO 
observatory. Observation started on 2022-05-22 (UT) 01:05:40. The series 
consists of images with an exposure of 60 s in a Clear filter.

The optical afterglow  (Malesani et al., GCN 32078; Fynbo et al., GCN 
32079; Goranskij et al., GCN 32082) is not detected in the stacked image.

Preliminary photometry of the stacked images is following

Date       UT start   t-T0    Filter Exp.    OT    err   UL(3)
                      (mid, days)       (s)

2022-05-22 01:05:40   0.07626  Clear 9*60    n/d  n/d   18.2


The photometry is based on nearby USNO-B1.0 (R2) stars
RA DEC R2
18:21:04.76880 +10:21:04.7232 16.26
18:21:07.39800 +10:20:37.5000 16.73