TITLE: GCN CIRCULAR NUMBER: 17696 SUBJECT: GRB 150413A: P60 photometry DATE: 15/04/14 04:41:01 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) and S. B. Cenko (GSFC) report: The Palomar 60-inch telescope observed the location of the optical counterpart of GRB 150413A (Markwardt et al., GCN 17688; Ivanov et al., GCN 17689) starting at 03:15:21 UT on 2015-04-14. We acquired 3x180s images in griz filters under good conditions. The optical transient is well-detected in all four filters. Calibrating relative to USNO stars in the field, we measure a magnitude of R = 19.1 (+/- 0.1) mag at this time (t = 0.560 days after the BAT trigger), indicating significant fading since the early observations. Further follow-up is planned.