TITLE: GCN CIRCULAR NUMBER: 9755 SUBJECT: GRB 090809: afterglow confirmation at the NOT DATE: 09/08/10 00:27:57 GMT FROM: Dong Xu at DARK,NBI D. Xu, G. Leloudas, D. Malesani, J.P.U. Fynbo (DARK/NBI), P. Jakobsson (Univ. of Iceland), and G. Furesz (CfA/Harvard) report on a larger collaboration: We observed the field of GRB 090809 (Markwardt et al., GCN 9754) with the Nordic Optical Telescope equipped with ALFOSC. We obtained 3x300 s I-band frames, starting on August 9th, 21:49:10 UT, 4.29889 hr after the burst; and 1x300 s R-band frame, starting 5.29861 hr after the burst. We confirm the presence of the UVOT source (Markwardt et al., GCN 9754) at coordinates: RA(J2000) = 21:54:43.17 Dec(J2000) = -00:05:01.9 which are consistent with the UVOT position. We note that the source is not visible in the archival SDSS frames of this field, thereby proving that it is the optical afterglow of GRB 090809. The afterglow is detected in each I-band and R-band frame. The preliminary magnitudes are I~19.9 and R~20.3 respectively, against the same reference star, 0899-0602834 in the USNO B1 catalog. Further photometric observations are underway. We encourage spectroscopic follow-up.