TITLE:   GCN CIRCULAR
NUMBER:  14914
SUBJECT: GRB 130612A: Continued Skynet/PROMPT/GORT/DSO observations
DATE:    13/06/17 23:14:09 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

M. Carroll, A. Trotter, J. Hailslip, D. Reichart, A. LaCluyze, K. McLin, 
L. Cominsky, A. Smith, D. Caton, L. Hawkins, T. Berger, H. T. Cromartie, 
R. Egger, A. Foster, C. Foster, N. Frank, K. Ivarsen, D. James, M. 
Maples, J. Moore, M. Nysewander, E. Speckhard, P. Taylor and J. A. Crain 
report

Skynet observed the Swift XRT localization of the field of GRB 130612A 
(Racusin et al., GCN 14874, Swift trigger #557976), beginning at 
2013-06-12, 3:23:27 UT (t=70s post-trigger), and continuing until t~5h, 
using three 16" telescopes of the PROMPT array at Cerro Tololo, Chile 
(BVI bands), the 14" GLAST Optical Robotic Telescope (GORT) at the Hume 
Observatory in California (RcIc bands), and the 14" telescope at the 
Appalachian State University Dark Sky Observatory (DSO-14) in Pisgah 
National Forest, North Carolina (RI bands). It took a total of ~500 
exposures ranging from 10s to 160s.

As we reported in Trotter et al. (GCN 14877), we detect a fading 
afterglow in the B, V and I bands out to t~1h at a position consistent 
with the detections of Racusin et al. (GCN 14874), Melandri, Mundell & 
Gomboc (GCN 14875), and Morgan (GCN 14876). In stacked images we obtain 
further detections in the V band at t=3.2h, and in the I band at t=1.5h 
and 1.9h.  The afterglow fades with an approximate temporal index 
alpha~-0.9.

A preliminary light curve is at:
http://skynet.unc.edu/grb/grb130612a_2.png

Magnitudes are in the Vega system, calibrated to 4 APASS stars in the 
field.  No correction has been applied for the expected line-of-sight 
Milky Way extinction E(B-V)=0.076 (Schlegel et al. 1998).

No further Skynet observations are scheduled.