TITLE: GCN CIRCULAR NUMBER: 9329 SUBJECT: GRB 090418A: optical observation DATE: 09/05/09 20:15:43 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev, E. Pavlenko(CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow of the Swift GRB 090418A (Mangano et al., GCN 9149) in I-filter on Apr. 20 (UT) 02:34:12 - 04:08:27 and in R-filter on Apr. 20 (UT) 21:03:05 - 22:49:20 with Shajn telescope of CrAO. We clearly detect afterglow in both epochs in stacked images. Preliminary photometry of Apr. 20 as well a photometry in V-filter of Apr. 18 observations (Pavlenko et al. GCN 9179) is following: T0+ Filter, Exposure, mag., err. UL Seeing (d) (s) 0.5476 V 17x60 22.3 +/- 0.2 23.2 1.9" 2.4507 R 70x60 22.8 +/- 0.1 24.4 1.9" Due to worse seeing (2.4") on Apr. 20 (UT) 02:34:12 - 04:08:27 the afterglow is evidently contaminated with nearby galaxy and photometry will be reported later. The photometry of Apr. 20 (UT) 21:03:05 - 22:49:20 also should be treated with caution due to possible contamination.