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.

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