TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5642 SUBJECT: GRB 060927: Early color DATE: 06/09/28 03:53:36 GMT FROM: Ken ichi Torii at Osaka U K. Torii (Osaka U.) reports on behalf of the ART collaboration: As we reported in GCN 5630, the error region of GRB 060927 (Barbier et al. GCN 5627) was observed with the 14 inch ART-3a (from 53 s after the burst in Ic band) and 0.35m ART-3b (from 112 s after the burst in Rc band) simultaneously. The optical afterglow (Schaefer et al. GCN 5629) was detected in the Ic band frames (Ic ~ 16.0 in the first 60 s exposure), but it was not detected in single Rc band frames. Combining our measurements and those reported in the circulars (GCN 5629; Zhai et al. GCN 5638), we roughly estimate the early Rc-Ic color redder (larger) than 1.5 and probably Rc-Ic ~ 2.0 at 100 s after the trigger time. This early color is consistent with that derived from later measurements at t ~ 300-1200 s (Guidorzi et al. GCN 5633; Sarugaku et al. GCN 5634; GCN 5638). The non detection in the UVOT white filter (GCN 5629) also suggests that the afterglow was red at t ~ 100 s. ===