TITLE: GCN CIRCULAR NUMBER: 19636 SUBJECT: GRB 160630A: Skynet PROMPT-CTIO observations of the optical afterglow DATE: 16/06/30 18:42:41 GMT FROM: Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet A. Trotter, D. Reichart, J. Haislip, J. Moore, N. Frank, M. Maples, D. Dutton, R. Gao, R. Joyner, J. Martin, M. Paggen, J. A. Crain, K. Ivarsen, A. LaCluyze, and M. Nysewander report: Skynet observed the Swift BAT/XRT localization of GRB 160630A (Krimm et al., GCN 19624, Swift trigger=702252) with with two 16" telescopes (P5, P6), and two 24" telescopes (P1, P8) of the PROMPT array at CTIO, Chile. Starting at 2016-06-30 04:05 UT and continuing until 07:02 UT (t=60s-3h post-trigger), Skynet took a total of 452 2.5-160s exposures in the I band (P1, P5), V band (P6) and B band (P8). We detect a fading optical afterglow in stacked I-band images at the OT position reported by Kann et al. (GCN 19625) and Melandri et al. (GCN 19627), with I~17.4 at t=5m and I~18.6 at t=23m. A preliminary light curve is at: http://www.skynet.unc.edu/grb/grb160630a.png Preliminary magnitudes are in the Vega System, calibrated to 9 APASS DR9 stars in the field. Magnitudes have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.43 (Schlafly & Finkbeiner 2011). No further Skynet observations are scheduled.