[vsnet-grb-info 13834] GRB 130831A: Skynet/PROMPT-SSO detections

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15148
SUBJECT: GRB 130831A: Skynet/PROMPT-SSO detections
DATE:    13/08/31 21:08:52 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter at physics.unc.edu>

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

Skynet observed the Swift/BAT localization of GRB 130831A (Hagen et al., 
GCN 15139, Swift trigger #568849) with four 17" telescopes of the 
newly-commissioned PROMPT array at Siding Spring Observatory, NSW, 
Australia. Starting at 2013-08-31, 13:39 UT and continuing until 17:41 
UT (t=35.5m-4.65h post-trigger), it took 615 80-s exposures in the BVRI 
bands. We detect a bright fading afterglow in all four bands at RA 
23:54:29.8, Dec 29:25:46.4 (J2000.0), within the error circle of the 
Enhanced Swift-XRT localization (Evans et al., GCN 15147).

A preliminary light curve is at:
http://skynet.unc.edu/grb/grb130831a.png

Magnitudes are in the Vega system, calibrated to 6 APASS stars in the 
field, and have not been corrected for the modest expected line-of-sight 
Milky Way dust extinction E(B-V)=0.046 (Schlegel et al. 1998).

Skynet observations are ongoing.