TITLE: GCN CIRCULAR NUMBER: 5741 SUBJECT: GRB060904b: optical observations DATE: 06/10/20 20:42:14 GMT FROM: Alexei Pozanenko at IKI, Moscow I. Asfandyarov, M. Ibrahimov (MAO), A. Pozanenko (IKI), on behalf of larger GRB follow up collaboration report: We observed the error box of GRB060904b (Grupe et al., GCN 5505) with 1.5 m telescope of Maidanak Astronomical Observatory (MAO) on September 4 and 5. A set of R images were taken under good weaher conditions. The afterglow (Rykoff et al., GCN 5504; Grupe et al., GCN 5505) is clearly detected in combined images of each epochs. A photometry of the afterglow based on USNO A2.0 is following: Mid time (UT), Exposure (s), R_ mag., Seeing Sep. 04.999 4x360 21.63 +/-0.18 1.4" Sep. 05.993 4x300 22.40 +/-0.30 1.1" The message may be cited