GCN Circular 14445
Subject
GRB 130420A: Continued Skynet/GORT Observations/Detections
Date
2013-04-25T22:19:25Z (11 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, N. Frank, A. LaCluyze, D. Reichart, K. McLin, L. Cominsky,
T. Berger, H. T. Cromartie, R. Egger, A. Foster, J. Haislip, K. Ivarsen,
M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:
Skynet continued observing the field of GRB 130420A (Page et al., GCN
14406, Swift trigger #553977) with the 14" GLAST Optical Robotic
Telescope (GORT) at the Hume Observatory in California. It took 214 80-s
exposures in Ic at times t=20.48-23.30h and t=26.25-28.56h after burst
trigger, and 96 80-s exposures in Rc at t=23.33-26.15h. We performed
photometry on the stacked exposures in each band, calibrated to six SDSS
stars in the field. We detect the afterglow in both Ic and Rc bands at
t~24h:
band exp length mean time since trig mag(Vega)
Ic 4.76h 24.37h 21.04 (+0.43,-0.31)
Rc 2.47h 24.77h 21.00 (+0.25,-0.21)
As we note in Trotter et al. (GCN 14427), and as Elenin et al. (GCN
14428) confirm, the afterglow exhibits a rising light curve at early
times, peaking at t=330s (peak Rc~16, Ic~15.5). After the peak, the
light curve fades with a power law index alpha~-0.9.
A preliminary light curve of the first and second nights' data is at:
http://skynet.unc.edu/grb/grb130420a_2.png
