GCN Circular 16967

A. Trotter, J. Haislip, D. Reichart, V. Hoette, K. Cudworth, D. Harper, 
R. Kron, T. Linder, R. Russell, E. Struble, 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 report:

Skynet observed the Swift BAT/XRT localization of GRB 141026A (Hagen et 
al., GCN 16950
Not found
 
 
, Swift trigger=616502) with one 24" telescope (PROMPT 8; 
I band) and four 16" telescopes (PROMPT 3,1,4,5; BVRI bands) of the 
PROMPT array at CTIO, Chile, and with the 41" telescope of Yerkes 
Observatory in Wisconsin, USA (g'r'i' bands).
Starting at 2014-10-26 02:38:30 UT and continuing until 03:03 UT 
(t=1.5-26m post-trigger), Skynet took a total of 89 exposures ranging 
from 10s-160s each. We stacked subsets of these images to maximize the 
S/N ratio, and detected no optical source in any band at the OT position 
first reported by RATIR (Littlejohns et al., GCN 16952
Not found
 
 
), and confirmed 
in later notices.  Our 3-sigma limiting magnitudes are:

==================================
tmid  scope   expos  fil  limit
==================================
10m  PROMPT3  4x80s   B   >19.9
20m  PROMPT1  4x160s  V   >20.4
19m  PROMPT4  3x160s  R   >19.8
17m  PROMPT5  4x80s   I   >19.9
               4X160s
17m  PROMPT8 12x80s   I   >20.0
63m  Yerkes   1x80s   g'  >21.2
               2x160s
60m  Yerkes   2x80s   r'  >20.9
               1x160s
66m  Yerkes   1x80s   i'  >20.5
               1x160s
==================================

BVRI magnitudes are in the Vega System, and g'r'i' magnitudes are in the 
AB system, calibrated to 4 APASS stars in the field.  Magnitudes have 
not been corrected for line-of-sight Milky Way dust extinction, with 
expected E(B-V)=0.16 (Schlafly & Finkbeiner 2011).

No further Skynet observations are scheduled.