TITLE: GCN CIRCULAR NUMBER: 9564 SUBJECT: GRB 090621A: GRT Optical Observation DATE: 09/06/23 02:08:36 GMT FROM: Takanori Sakamoto at NASA/GSFC 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 090621A detected by Swift (trigger #355303; Curran et al., GCN #9540) 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 21 05:00:15 (UT) about 37.3 min after the trigger and stopped on June 21 05:56:22 (UT). We do not detect the optical afterglow both in the individual images and the combined image inside the XRT position (Page et al., GCN #9543). The estimated three sigma upper limit of the combined image (total exposure of 2850 sec; excluding five bad quality images) is ~17.9 mag using the USNO-B1 catalog.