TITLE: GCN CIRCULAR NUMBER: 17145 SUBJECT: GRB141121A: Discovery Channel Telescope Optical Observations DATE: 14/12/07 21:48:55 GMT FROM: Vicki Toy at UMD V. Toy (UMD), J. Capone (UMD), A. Cucchiara (NASA-GSFC), S.B. Cenko (NASA-GSFC), E. Troja (NASA-GSFC), A. Kutyrev (NASA-GSFC), and S. Veilleux (UMD) report on behalf of a larger collaboration: We observed the field of GRB141121A (Swift trigger 619182, Lien et al., GCN 17075) with the Large Monolithic Imager (LMI) on the 4.3m Discovery Channel Telescope (DCT) at Happy Jack, AZ from 2014/12/07 6:44 to 2014/12/07 11:01 UTC (starting 386.1 hours after the Swift trigger). A source is clearly detected at the location of the optical afterglow in g', r', i', and z'. Using nearby point sources from SDSS R8 for calibration we measure i' = 23.26 +/- 0.12. This magnitude is reported in AB magnitude and is not corrected for Galactic extinction in the direction of the GRB. Compared to RATIR observations on 12/01 (Watson, GCN 17128) the afterglow has steepened to a decay index of ~ t^-2.1. At this time we cannot confirm if this is the host galaxy. Further observations are planned. We thank the staff of the Discovery Channel Telescope for assistance with these observations.