GCN Circular 10335
A. Cucchiara, D. B. Fox (PennState), E. Berger (Harvard U.) report on behalf of a larger collaboration: "On January 16.20 UT we observed the field of GRB100115A (Cummings et al. 10325, Margutti et al. GCN 10326) with the Gemini-North GMOS camera in r and g bands. We collected a sequence of 5x180s images in each filter. In the coadded images the afterglow candidate is visible in both filters (GCN 10328,10331,10332). On January 17.20 UT we collected a second epoch with the same set-up. The following magnitude have been calibrated using the USNO-B1.0 star at RA: 00:13:30.44 Dec: -00:49:16.93 ( = 19.76 mag): Jan. 16.20 UT: r = 21.37 +- 0.08 mag Jan 17.20 UT: r = 21.86 +- 0.08 mag A similar fading of ~0.5 mag is present in our g-band observations. Therefore we conclude that Object "A", which shows two structures, contains a fading transient. Further observation are planned. We thank the Gemini staff, in particular Sandy Leggtt, for performing these observations.