TITLE: GCN CIRCULAR NUMBER: 35839 SUBJECT: GRB 240225B: further SAO RAS optical observations DATE: 24/02/29 18:48:28 GMT FROM: Moskvitin Alexander at SAO RAS mosk@sao.ru

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

We observed the field of GRB 240225B (Nakajima et al., GCN 35796; Evans, GCN 35797; Joshi et al., GCN 35798; D'Ai et al., GCN 35810; Kawakubo et al., GCN 35811; Frederiks et al., GCN 35835) with the SAO RAS 1m telescope Zeiss-1000 equipped with CCD-photometer. We obtained 8 x 300 sec frames in the Rc band on Feb. 29, 17:11:52--18:03:46 UT (t_mid - T0 = 3.8903 days).

The OT (Gompertz et al., GCN 35805; Liu et al., GCN 35812; Malesani et al., GCN 35819; Wise et al., GCN 35820; Gompertz & Malesani, GCN 35824; Pankov et al., GCN 35826; Ror et al., GCN 35830; Sasada et al., GCN 35831; Schneider et al., GCN 35832) is clearly detected in our stacked frame with the brightness of R = 21.11 +/- 0.04.

The photometry is based on nearby SDSS stars (magnitudes converted with Lupton 2005 equations).

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