TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2680 SUBJECT: GRB 040827: Possible detection of optical afterglow DATE: 04/08/28 01:26:44 GMT FROM: Edo Berger at Carnegie Obs E. Berger, Ian Thompson (Carnegie Observatories) and Wojtek Krzeminski (Las Campanas Observatory) report: "We imaged the 2.5-arcmin error circle of GRB 040827 (GCN #2672) with the Swope 40-inch telescope at Las Campanas Observatory (LCO) from August 27.98 to 28.02 UT (12.2 hours after the burst) for a total of 40 minutes on source. Observations were taken in the I-band in good weather conditions and seeing of about 1.1 arcsec. We do not detected any strong sources within the 10-arcsec error circle of the XMM-Newton X-ray source (GCN #2678), but a weak source (~4-sigma) is detected about 4.7" from the center of the XMM error circle with I=21.8 mag (compared to USNO-B1) at: RA= 15:17:01.4 DEC= -16:08:23.3 (J2000) with an uncertainty of about 0.3" in each coordinate."