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:
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.