TITLE: GCN CIRCULAR NUMBER: 8788 SUBJECT: GRB 090107B optical observations DATE: 09/01/07 17:53:05 GMT FROM: Arne A. Henden at AAVSO Arto Oksanen (Hankasalmi Obs., Hankasalmi, Finland) reports via the AAVSO High Energy Network the following optical observations of the INTEGRAL burst GRB 090107B (Gotz et al., GCN Circular #8786): Unfiltered observations were made using a 0.4-meter RC telescope with an SBIG STL-1001E CCD. The full INTEGRAL error box was observed unfiltered starting at 16:35UT, 15 minutes after the burst. Combining ten 60-second exposures, we do not see any optical afterglow to a limiting magnitude of 20.5 (compared with the DSS2 red plate). A FITS image of this observation is available at the following URL: ftp://ftp.aavso.org/grb/ArtoOksanen_GRB090107_2454839.23238_.fits The AAVSO thanks the Curry Foundation for their continued support of the AAVSO International High Energy Network.