[vsnet-grb-info 14177] GRB 131117A: Skynet PROMPT optical detection of an afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15491
SUBJECT: GRB 131117A: Skynet PROMPT optical detection of an afterglow
DATE:    13/11/17 02:21:48 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter at physics.unc.edu>

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

Skynet observed the Swift/XRT localization of GRB 131117A (Page et al., 
GCN 15490, Swift trigger 577968) with four 14" telescopes of the PROMPT 
array at Cerro Tololo, Chile, beginning 91s after the trigger, 
simultaneously in the BVRI bands. We detect a fading optical source in 
V, R and I bands at:
RA 22:09:19.3
Dec -31:45:44.4 (J2000.0)
which is within the error circle reported by the Swift XRT.  The 
afterglow fades from R~17.2 at t=1.5min to R~19.7 at t=24min.

Photometry is calibrated to six APASS-DR7 stars in the field, and has 
not been corrected for Galactic foreground extinction.

A preliminary light curve is at: http://skynet.unc.edu/grb/grb131117a.png

Skynet observations are ongoing.