GCN Circular 9565
T. Sakamoto (UMBC/GSFC), D. Donato (ORAU/GSFC), N. Gehrels (GSFC), T. Okajima (JHU/GSFC), T.N. Ukwatta (GWU/GSFC), Y. Urata (NCU), C.A. Wallace (FGCU) We observed the field of GRB 090621B detected by Swift (trigger #355359; Curran et al., GCN #9545) with the 14-inch Goddard Robotic Telescope (GRT) located at the Goddard Geophysical and Astronomical Observatory (http://cddisa.gsfc.nasa.gov/ggao/). 100 set of 30 sec exposures were taken in the R filter starting from June 22 01:51:44 (UT) about 3.7 hours after the trigger and stopped on June 22 02:47:51 (UT). We do not detect the optical afterglow both in the individual images and the combined image inside the XRT position (Beardmore et al., GCN #9550). The estimated three sigma upper limit of the combined image (total exposure of 2880 sec; excluding four bad quality images) is ~17.8 mag using the USNO-B1 catalog.