TITLE: GCN CIRCULAR NUMBER: 12190 SUBJECT: GRB 110709B / EVLA detection of radio counterpart DATE: 11/07/21 22:04:14 GMT FROM: Ashley Zauderer at CfA A. Zauderer and E. Berger (Harvard/CfA) report on behalf of a larger collaboration: "We observed GRB 110709B (GCN 12122) with the EVLA on several occasions between 2011 July 11 and 16 UT at a frequency of 5.8 GHz. Within the XRT error circle (GCN 12136) we find a single unresolved radio source which brightened by about a factor of 1.6 between 2.1 and 7.0 days after the burst. The source is located at (J2000): RA = 10:58:37.114 Dec = -23:27:16.760 The coincidence with the XRT position and the rising flux indicate that this source is the radio afterglow of GRB 110709B. No optical counterpart is detected at this position in our Gemini r-band observations (GCNs 12132, 12155) to a limit of >23.8 mag at 3.2 hours and >25.1 mag at 4.1 days. Along with the bright X-ray counterpart, the radio source provides additional support that GRB 110709B is a dark burst. We thank the EVLA staff for their support of these observations."