TITLE: GCN CIRCULAR NUMBER: 20202 SUBJECT: GRB 161117A: SMARTS optical/IR afterglow observations DATE: 16/11/22 01:11:47 GMT FROM: Bethany Cobb at GWU B. E. Cobb (GWU), reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 161117A (GCN 20179, Cummings et al.) at two epochs (with mid-exposure times of 2016-11-17 02:38 UT & 2016-11-18 01:47 UT). For each epoch, several dithered images were obtained with total summed exposure times of 15 min in V and I and 12 min in J and K. The fading afterglow of GRB 161117A (e.g. GCN 20179, Cummings et al.; GCN 20180, Malesani et al.; GCN 20181, D'Avanzo et al.) was detected with the following preliminary magnitudes (or 3-sigma limits): mid-exposure time post-burst (hours) V mag I mag J mag K mag 1.03333 19.42+/-0.10 18.69+/-0.07 18.40+/-0.15 16.49+/-0.11 24.19361 >22.3 >21.1 >18.5 >16.7 (Optical photometry is calibrated against Landolt standard stars and IR photometry is calibrated against 2MASS stars in the field.)