GCN Circular 16304
Subject
GRB 140518A: Skynet GORT Detections of the Optical Afterglow
Date
2014-05-18T18:24:41Z (10 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, A. LaCluyze, J. Haislip, D. Reichart, K. McLin, L. Cominsky,
H. T. Cromartie, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore,
M. Nysewander, R. Beauchemin, T. Berger, A. Dow, M. Hinckle, A.
Patterson, H. Pegues, J. Pozo, D. Waddell, and J. A. Crain report:
Skynet observed the Swift-XRT localization of GRB 140518A (Melandri et
al., GCN 16298, Swift trigger 599287) with the 14" GLAST Optical Robotic
Telescope (GORT) at the Hume observatory in CA, USA. Observations began
at t=130s and continued until 2.4h post-trigger. Skynet took alternating
exposures in the Rc and Ic bands, increasing from 10s to 160s. In early
Ic and Rc images, and in later stacked Ic images, we detect an
uncatalogued fading optical source at a position consistent with the
afterglow candidate reported by Zheng et al. (GCN 16299).
The source faded from Ic=16.8 at t=130s to Ic > 18.7 at a mean time
t~70m. In Rc band, we detect the source marginally at Rc~18.3 at t=4m,
with Rc>20.1 at a mean time t~55m.
A preliminary light curve is at:
http://www.skynet.unc.edu/grb/grb140518a.png
Photometry is calibrated to six APASS-DR7 stars in the field, and has
not been corrected for the Galactic foreground extinction corresponding
to E(B-V)=0.016 (Schlegel et al. 1998).
No further Skynet observations are scheduled.
