A. Trotter, J. Haislip, D. Reichart, A. Aji, R. Beauchemin, T. Berger,
A. Dow, A. Foster, N. Frank, M. Hinckle, K. Ivarsen, A. LaCluyze, M.
Maples, J. Moore, M. Nysewander, C. Salemi, L. Zbinden, and J. A. Crain
Skynet continued to observe the Swift UVOT localization of GRB 141221A
(Sonbas et al., GCN 17206, Swift trigger=622006) with two 16" telescopes
of the PROMPT array at Cerro Tololo, Chile. Starting at 2014-12-22 07:08
UT and continuing until 08:34 UT (t=23.0h-24.5h post-trigger), Skynet
took a total of 64 exposures of 160s each in the V and I bands. We
stacked subsets of these images to maximize the signal-to-noise ratio.
We no longer detect the optical afterglow that we described in Trotter
et al. (GCN 17210).
Our limiting magnitudes are:
tmid expos fil limit
23.8h 32x160s V >21.2
23.8h 31x160s I >20.7
A preliminary light curve is at:
Magnitudes are in the Vega System, calibrated to 3 APASS stars in the
field. Magnitudes have not been corrected for line-of-sight Milky Way
dust extinction, with expected E(B-V)=0.024 (Schlafly & Finkbeiner 2011).
No further Skynet observations are scheduled.