TITLE:   GCN CIRCULAR
NUMBER:  15235
SUBJECT: GRB 130919A: Skynet PROMPT-CTIO optical upper limits
DATE:    13/09/20 04:04:19 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, J. Moore, N. Frank, K. 
Ivarsen, M. Nysewander, A. Foster, T. Berger, H. T. Cromartie, R. Egger, 
M. Maples, and J. A. Crain report:

Skynet observed the Swift-BAT localization of GRB 130919A (Krimm et al., 
GCN 15232; Lien et al., GCN 15234, Swift trigger=571271) with three 16" 
telescopes of the PROMPT array at CTIO, Chile (V, R, and I bands).

Starting at 2013-09-19, 23:29 UT and continuing until 2013-09-20, 00:00 
UT (t=12.40-12.93h post-trigger), Skynet took a total of 49 160s 
exposures, at high airmass >3. In stacked images, we do not detect any 
uncatalogued optical source in any band in or near the Swift-BAT error 
circles.  The 3-sigma limiting magnitudes of our images are:

==================================
tmid    scope   expos   fil  limit
==================================
12.67h  Prompt5 12x160s  I  >19.44
12.55h  Prompt4  7x160s  R  >19.24
12.63m  Prompt1 10x160s  V  >19.54
==================================

Magnitudes are in the Vega System, calibrated to 8 APASS-DR7 stars in 
the field.  Magnitudes have not been corrected for line-of-sight Milky 
Way dust extinction, with expected E(B-V)=0.057 (Schlegel et al. 1998).

No further Skynet observations are scheduled.