TITLE: GCN CIRCULAR NUMBER: 10557 SUBJECT: GRB 100331A: BOOTES-3 observations DATE: 10/03/31 10:13:18 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (INAF-OAB), A.J. Castro-Tirado, J. Gorosabel, M. Jelinek (IAA-CSIC), P. Kubanek (IPL UV, IAA-CSIC), R. Cunniffe, S. Guziy (IAA-CSIC), P. Yock (Auckland Univ.), W.H. Allen (Vintage Lane Obs.), I. Bond (Massey Univ.), G. Christie (Stardome Obs.), report on behalf of a larger collaboration, report: We have observed the field of the INTEGRAL GRB 100331A (Mereghetti et al. GCN 10555) using the 0.6 Yock-Allen robotic telescope (BOOTES-3) located in Blenheim, New Zealand starting at 07:12 UT (6.7 hours after the burst). In a 35x60s combined exposure with clear filter, obtained under non optimal conditions, we do not detect any new source within the full INTEGRAL error circle down to a 3-sigma limiting magnitude of R~17.8. Further analysis is ongoing.