TITLE:   GCN CIRCULAR
NUMBER:  14901
SUBJECT: GRB 130615A: Skynet/PROMPT Observations
DATE:    13/06/15 17:58:55 GMT
FROM:    Nathan Frank at U.North Carolina  <nrfrank@live.unc.edu>

N. Frank, A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, T. Berger, M. Carroll, H. T. Cromartie, R. Egger, A. Foster, C. Foster, 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 130615A (Sonbas et al., GCN 14897, Swift trigger #558271), starting at 2013-06-15, 09:46:37 UT (t=1.86m post-trigger), with four 16" telescopes of the PROMPT array at CTIO, Chile.  We detect an uncataloged optical source in B, V, R and I bands at: RA = 18:19:19.08, Dec = -68:09:41.02 (J2000.0), consistent with the GROND (Elliott et al., GCN 14898) and enhanced Swift/XRT positions (Evans et al., GCN 14900).

Calibrating to 6 APASS stars in the field we find an average magnitude of R~20.4 over the time period between t~8m and t~46m. The time range and sensitivity of these observations is not sufficient to determine if the source is fading with time. A preliminary light curve is at:
http://skynet.unc.edu/grb/grb130615a.png

Skynet observations are scheduled to determine if the source is indeed fading.