TITLE: GCN CIRCULAR NUMBER: 9323 SUBJECT: GRB 090423: optical limit DATE: 09/05/05 00:21:38 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev, E. Pavlenko, O. Antoniuk (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the error box of Swift GRB 090423 (Krimm et al. GCN 9198) on Apr. 23 between (UT) 090423 23:34:46 -- 090424 01:13:20 in R -filter with Shajn telescope of CrAO. The observation was planning and performed before the redshift z ~ 8 of GRB 090423 was confirmed (Cucchiara et al. GCN 9213; Olivares et al. GCN 9215; Thoene et al. GCN 9216; Tanvir et al. GCN 9219). Indeed we do not detect optical afterglow at the place of IR afterglow detection (Tanvir et al. GCN 9202; Levan et al. GCN 9206; Cucchiara et al. GCN 9209). Limiting magnitude of the combined image is following : T0+ Filter, Exposure, mag., err. (d) (s) 0.6877 R 93x60 >24.0 (3 sigma) The combined R-image can be found at http://grb.rssi.ru/GRB090423/GRB090423_ZTSh_a.gif