The field of GRB 100628A as seen by ATCA in the 5.5 GHz band overlaid in Fig. 1. Radio contour levels (in magenta) run from F_ν = 10 to 25 μJy in steps of 2.5 μJy and then from 30 to 100 μJy in steps of 10 μJy. The size of the synthesized beam is (upper left corner). Inside the XRT error circle, we do not detect object C, but we detect emission close to object A (see text for details). In addition, we detect object D as a bright point source. Overlaid are the optical contours (white).