TITLE: GCN CIRCULAR NUMBER: 9656 SUBJECT: GRB 090621B: MTM-500 optical observations DATE: 09/07/11 20:19:43 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), A. Volnova (SAI MSU), V. Kouprianov, Ya. Naiden, V. Slesarenko, A. Devyatkin (Pulkovo Observatory), report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 090621B (Curran et al, GCN 9545) with MTM-500 telescope of Kislovodsk solar station of the Pulkovo observatory in two series in R-filter between (UT) 2009-06-21 22:31 - 2009-06-22 00:01, i.e. starting ~24 minutes after burst onset. The upper limit of a stacked image of first 15 frames based on USNO B1.0 stars is following T0+ Filter Exp. mag. (mid, d) s 0.02147 R 15x60 >18.5 (3 sigma) While we do not detect objects reported in GCN 9547 (Levan et al.) and GCN 9549 (Galeev et al.) in the stacked image above, we may suggest a possible object near the edge of the refined XRT error box (Beardmore et al., GCN 9550) in coordinates (J2000) RA = 20:53:53.24 Dec = +69:01:45.5. This possible object appears more intense in the stacked image of the first five frames, and does not appear in the second epoch of our observations started on Jun.21 (UT) 23:37. Due to low S/N ratio we cannot confirm the object is real. We encourage re-analysis of later deep observations to clarify the nature of the object. The finding chart can be found at http://grb.rssi.ru/GRB090621B/grb090621B_MTM.png , where source labeled #5 is the USNO B1.0 star 1590-0172172 (RA(J2000)=20:53:57.28, Dec(J2000)=+69:01:47.8, R2=19.41)