TITLE:   GCN CIRCULAR
NUMBER:  37346
SUBJECT: GRB 240828B: SAO RAS optical upper limit
DATE:    24/08/30 00:10:12 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

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

We observed the field of GRB 240828B (Le Provost et al., GCN 37318)
with the SAO RAS 1-meter telescope Zeiss-1000 equipped with
the CCD-photometer on August 29, 19:36:46 -- 20:00:01 UT
(t_mid - T0 = 30.594 hours = 1.2748 days). We obtained several images
in Rc band with a total exposure of 1040 seconds.

Within the XRT error circle (Page et al., GCN 37334) we didn't detect
any source down to a limiting magnitude of R_lim = 21.0 as well as
KAIT team (Zheng et al., GCN 37345).

The field was calibrated against nearby SDSS stars (magnitudes
converted with Lupton 2005 equations) and not corrected for the Galaxy
extinction.