TITLE: GCN CIRCULAR NUMBER: 32548 SUBJECT: GRB 220831A: DECam optical counterpart follow-up DATE: 22/09/12 07:33:12 GMT FROM: Anais Moller at Australian National U GRB 220831A: DECam optical counterpart follow-up J. Freeburn, N. Van Bemmel, D. Dobie, A. Moller, J. Cooke (Swinburne/OzGrav), M. Suhr (Swinburne/ASTRO 3D), S. Webb (Swinburne) report on behalf of the Deeper, Wider, Faster Collaboration We have carried out additional observations further to GCN 32516 of the optical counterpart (RA = 01:37:0.965, DEC = -41:35:34.60) to GRB220831A (GCN 32506). Here we present source observations using the Dark Energy Camera (DECam) on the V. M. Blanco 4-m telescope and revised, forced photometry of our previous observations using NOAO calibrated images. Images were taken in g, r, i on UT dates 2022-08-31 to 2022-09-04 as additional observations during the Deeper, Wider, Faster (DWF) program observing run. Our photometry, along with those of Gordon et al. (GCN 32535) and D'Avanzo et al. (GCN 32513) are consistent with current short GRB optical afterglow models. The following detection and upper limits (not corrected for Galactic extinction): T-start (MJD) filter detection/UL 59823.200 g 23.17 +/- 0.18 59823.203 r 22.885 +/- 0.088 59823.209 i 23.06 +/- 0.13 59823.384 g 23.72 +/- 0.30 59823.395 r 23.37 +/- 0.13 59823.389 i 23.12 +/- 0.13 59824.198 g 24.33 +/- 0.37 59824.203 r 24.69 +/- 0.35 59824.208 i 23.86 +/- 0.22 59824.377 g 24.94 +/- 0.59 59824.390 r 24.13 +/- 0.25 59824.391 i 24.10 +/- 0.25 59825.300 r >24.8 59825.301 i >24.4 59826.306 i >25.0