TITLE: GCN CIRCULAR NUMBER: 1699 SUBJECT: GRB 021113: Evidence for a Dark Optical Afterglow DATE: 02/11/19 18:54:16 GMT FROM: Melissa Nysewander at UNC,Chapel Hill M. Nysewander, D. Reichart (U. North Carolina), and M. Schwartz (Tenagra Observatories) report on behalf of a larger collaboration: We observed 100% of the 23 arcmin x 13 arcmin error box, but only 90% of the revised 26 arcmin x 9 arcmin error box, of GRB 021113 (GCN 1686) with the 32-inch Tenagra II telescope beginning 2.6 hours (GCN 1687) and 22.3 hours after the burst. For each epoch, we integrated without filter for 1800 seconds per pointing x two pointings under photometric conditions. Due to more favorable airmasses, the second epoch observations went deeper. Calibration images of M67 suggest that unfiltered magnitudes measured with this CCD best mimic R magnitudes (Henden 2000). Using the image subtraction routine ISIS2 (Alard 2000), we find no transients to the limiting magnitude of our first epoch image, which we measure to be R = 21.5 mag (5 sigma), 22.1 mag (3 sigma), and 23.2 mag (1 sigma) using the following three USNO-A2.0 stars: RA (hrs) DEC (deg) R (mag) 23.353 40.522 13.8 23.425 40.341 13.9 23.342 40.483 16.7 This is the deepest non-detection of an optical afterglow within four hours of a burst. Alard, C., 2000, A&AS 114, 363 Henden, A., 2000, JAAVSO 29, 35