TITLE: GCN CIRCULAR NUMBER: 16901 SUBJECT: GRB 141005A: Additional P60 imaging and afterglow confirmation DATE: 14/10/07 06:04:59 GMT FROM: Daniel Perley at Caltech S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) report: We obtained a second epoch of imaging at the location of the optical afterglow (Perley et al., GCN 16884; Littlejohns et al., GCN 16885; Schmidl et al., GCN 16898) of GRB 141005A (D'Elia et al., GCN 16882) with the robotic Palomar 60 inch telescope. Observations were obtained in the r', i', and z' filters beginning at 2:31 UT on 2014 October 6 (0.89 d after the burst). A source is clearly detected at the location of the afterglow candidate originally reported in GCN 16884 (Perley et al). As noted therein, a source is also present at this location in pre-outburst SDSS imaging of this field. To search for variability at this location, we performed digital image subtraction with the P60 data, using the images from 2014 October 6 as a reference template. We find clear evidence for fading in the i-band (and marginal evidence in r and z-bands), confirming that this source is indeed the optical afterglow of GRB 141005A but is blended with a bright (i' ~ 21.7 mag) host galaxy or foreground object. Assuming no contribution of the afterglow to our template images, we measure i' = 20.24 +/- 0.10 at 5:18 UT on 2014 October 5 (i.e., 5 min after the Swift trigger).