TITLE:   GCN CIRCULAR
NUMBER:  14826
SUBJECT: GRB 130606A: Continued Skynet/PROMPT observations
DATE:    13/06/08 18:21:21 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, A. LaCluyze, D. Reichart, J. Haislip, T. Berger, M. Carroll, 
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 continued observing the field of GRB 130606A (Ukwatta et al., GCN 
14781, Swift trigger #557589), using the optical localization of Xu et 
al. (GCN 14783).  It took 109 160-second exposures in the z' band with 
one of the 16" telescopes of the PROMPT array at CTIO, Chile, with a 
mean time t=1.3d post-trigger.

In a stack of all 109 exposures, we detect the afterglow at the 5-sigma 
level, with z'~20.5 at t=1.3d.  Together with the z' detections we 
reported in Trotter et al. (GCN 14815), this implies an approximate 
temporal index alpha~-1.2.   A preliminary light curve of both nights' 
data is at:
http://www.skynet.unc.edu/grb/grb130606a_2.png

Photometry is calibrated to 10 SDSS stars in the field; g' and z' 
magnitudes are in the AB system; R-band magnitudes are in the Vega 
system, with the SDSS calibration stars transformed according to Jester 
(2005).  No correction has been applied for the expected line-of-sight 
Milky Way extinction of E(B-V)=0.02 (Schlegel et al. 1998).

No further Skynet observations are scheduled.