GCN Circular 15164
Subject
GRB 130831A: Continued Skynet/PROMPT-SSO, PROMPT-CTIO and Yerkes-41 detections
Date
2013-09-02T01:57:04Z (12 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, J. Moore, N. Frank, V.
Hoette, D. Harper, R. Kron, K. Cudworth, E. Struble, R. Russell, T.
Berger, H. T. Cromartie, R. Egger, A. Foster, K. Ivarsen, M. Maples, M.
Nysewander, and J. A. Crain report:
Skynet continued observing the Swift-XRT localization of GRB 130831A
(Hagen et al., GCN 15139, Swift trigger 568849) with the four 17"
telescopes of the PROMPT array at Siding Spring Observatory, NSW,
Australia, four 16" telescopes of the PROMPT array at Cerro Tololo,
Chile, and the 41" telescope of Yerkes Observatory in Wisconsin, USA.
Starting at 2013-08-31, 13:39 UT and continuing until 2013-09-01, 17:40
UT (t=35.5m-28.2h post-trigger), Skynet took a total of 2,227 exposures
of 60-160s in the BVRI (PROMPT) and g'i' bands (Yerkes). As we reported
in Trotter et al. (GCN 15148), we detect a bright fading afterglow in
all 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).
We continue to detect a fading afterglow in stacked images, with R~20
mag at t~15h, and R~20.6 mag at t~25h.
A preliminary light curve that includes our first-day PROMPT-CTIO and
Yerkes data, and our second-day PROMPT-SSO data is at:
http://skynet.unc.edu/grb/grb130831a_2.png
BVRI magnitudes are in the Vega system, and g'i' magnitudes are in the
AB system, calibrated to 3 APASS stars in the field. Photometry has 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.