TITLE: GCN CIRCULAR NUMBER: 10603 SUBJECT: GRB 100414A: Palomar Transient Factory Observations DATE: 10/04/16 22:06:46 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko (UC Berkeley), A. Rau (MPE Garching), E. O. Ofek (Caltech), P. E. Nugent (LBNL), J. Greiner (MPE Garching), and S. R. Kulkarni (Caltech) report on behalf of a larger collaboration: We have imaged the Fermi-LAT localization of GRB 100414A (Takahashi et al., GCN 10594; Foley, GCN 10595) with the automated Palomar 48 inch Schmidt telescope as part of the Palomar Transient Factory (PTF; Law et al, PASP, 1395; Rau et al, PASP 121, 1334) survey. A 60 s R-band image was obtained beginning at 7:53 UT on 15 April 2010 (~ 29.5 hours after the burst trigger), followed approximately an hour later by another 60 s image of the identical field. Digital subtraction with respect to a stacked pre-explosion P48 reference image reveals no afterglow candidate to a limiting magnitude of R > 21.0 mag within the 90% LAT localization region (Takahashi et al., GCN 10594). We note, however, that our imaging does not cover the location of the potential XRT afterglow candidate identified by Page et al. (GCN 10601).