GCN Circular 10407
M. Im (CEOU/Seoul National Univ) and Y. Urata (NCU) on behalf of EAFON team. We observed GRB100212A (Grupe et al. GCN 10401) in R and V using the 1.0m telescope at Mt. Lemmon (Arizona, US) operated by the Korea Astronomy Space Science Institute. The observation started at Feb. 13, 02:05:14 UT, about 12 hours after the BAT trigger. The stacked R-band image shows a marginal detection of the afterglow with R ~ 22.5 +- 0.2 mag, at the location reported by Malesani et al. (GCN 10402). The mid-point for the R-band imaging is 02:17:36 UT. The object does not appear in a stacked V-band image, which was taken right after the R-band observation. Our obseravation shows that the afterglow candidate faded significantly since the report by Malesani et al. (GCN 10402), confirming that this is indeed a GRB afterglow. The photometry was calibrated against the USNO star (GCN 10402). We thank the LOAO operator, J. Yoon for her assistance of this observation.