GCN Circular 15193
Subject
GRB 130907A: Skynet DSO-14/Yerkes-41/GORT confirmation of a fading afterglow
Date
2013-09-08T06:28:32Z (11 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, K. McLin, L. Cominsky,
A. B. Smith, D. Caton, L. Hawkins, V. Hoette, K. Cudworth, D. Harper, R.
Kron, T. Linder, R. Russell, E. Struble, T. Berger, H. T. Cromartie, R.
Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore, M.
Nysewander, and J. A. Crain report:
In Trotter et al. (GCN 15191), we reported Skynet observations of the
Swift/XRT localization of GRB 130907A (Page et al., GCN 15183, Swift
trigger 569992) with the 14" telescope at the Appalachian State
University Dark Sky Observatory (DSO-14) in NC, USA (R and I bands), and
with the 41" telescope of Yerkes Observatory in WI, USA (r' and i'
bands). Skynet continued observing the field with the 14" GLAST Optical
Robotic Telescope (GORT) at the Hume observatory in CA, USA.
From t=5.9h - 8.2h post-trigger, GORT took a total of 54x160s exposures
in the R and I bands. We confirm a fading afterglow at the position
reported by de Ugarte Postigo et al. (GCN 15187) and by Lee et al. (GCN
15192). The afterglow fades from I=18.1 mag at t=3.2h to I=19.2 mag at
t=8.2h, consistent with a power-law index alpha~-0.9.
A preliminary light curve is at:
http://skynet.unc.edu/grb/grb130907a_2.png
R and I magnitudes are in the Vega system, and r' and i' magnitudes are
in the AB system, calibrated to 5 APASS stars in the field. Magnitudes
have not been corrected for line-of-sight Milky Way dust extinction,
with expected E(B-V)=0.011 (Schlegel et al. 1998).
No further Skynet observations are scheduled.
