{
  "bibcode": "2013GCN.15164....1T",
  "body": "A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, J. Moore, N. Frank, V. \nHoette, D. Harper, R. Kron, K. Cudworth, E. Struble, R. Russell, T. \nBerger, H. T. Cromartie, R. Egger, A. Foster, K. Ivarsen, M. Maples, M. \nNysewander, and J. A. Crain report:\n\nSkynet continued observing the Swift-XRT localization of GRB 130831A \n(Hagen et al., GCN 15139, Swift trigger 568849) with the four 17\" \ntelescopes of the PROMPT array at Siding Spring Observatory, NSW, \nAustralia, four 16\" telescopes of the PROMPT array at Cerro Tololo, \nChile, and the 41\" telescope of Yerkes Observatory in Wisconsin, USA. \nStarting at 2013-08-31, 13:39 UT and continuing until 2013-09-01, 17:40 \nUT (t=35.5m-28.2h post-trigger), Skynet took a total of 2,227 exposures \nof 60-160s in the BVRI (PROMPT) and g'i' bands (Yerkes). As we reported \nin Trotter et al. (GCN 15148), we detect a bright fading afterglow in \nall bands at RA 23:54:29.8, Dec 29:25:46.4 (J2000.0), within the error \ncircle of the Enhanced Swift-XRT localization (Evans et al., GCN 15147).\n\nWe continue to detect a fading afterglow in stacked images, with R~20 \nmag at t~15h, and R~20.6 mag at t~25h.\n\nA preliminary light curve that includes our first-day PROMPT-CTIO and \nYerkes data, and our second-day PROMPT-SSO data is at:\nhttp://skynet.unc.edu/grb/grb130831a_2.png\n\nBVRI magnitudes are in the Vega system, and g'i' magnitudes are in the \nAB system, calibrated to 3 APASS stars in the field. Photometry has not \nbeen corrected for the modest expected line-of-sight Milky Way dust \nextinction E(B-V)=0.046 (Schlegel et al. 1998).\n\nSkynet observations are ongoing.",
  "circularId": 15164,
  "createdOn": 1378087024000,
  "email": "atrotter@physics.unc.edu",
  "subject": "GRB 130831A: Continued Skynet/PROMPT-SSO, PROMPT-CTIO and Yerkes-41 detections",
  "submitter": "Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>",
  "eventId": "GRB 130831A"
}