TITLE: GCN CIRCULAR NUMBER: 35323 SUBJECT: GRB 231210B: MeerLICHT afterglow observations DATE: 23/12/11 21:11:37 GMT FROM: Simon de Wet at University of Cape Town <simdewet@gmail.com> S. de Wet (UCT), P.M. Vreeswijk (Radboud) and P.J. Groot (Radboud/UCT/SAAO) report on behalf of the MeerLICHT consortium: The 0.6 m wide-field MeerLICHT optical telescope located in Sutherland, South Africa, obtained a repeated series of 60 s exposures in the q,u,g,r,i,z bands of GRB 231210B following the Swift detection (Page et al., GCN 35314). Observations started at 21:32:26 UT on 2023 November 18 (202 seconds post-trigger) and continued for a further 1.79 hours, following the filter sequence quqgqrqiqz. We detect the optical afterglow also detected by MASTER, UVOT, LCOGT, and the VLT (Buckley et al., GCN 35313; Page et al., GCN 35314; Pérez-Fournon et al., GCN 35316; Saccardi et al., GCN 35317) with the following AB magnitudes: q = 17.15 +/- 0.02 at 21:32:57 UT u = 19.67 +/- 0.19 at 21:34:20 UT g = 18.69 +/- 0.04 at 21:37:17 UT r = 18.11 +/- 0.03 at 21:40:11 UT i = 18.15 +/- 0.05 at 21:43:08 UT z = 18.30 +/- 0.11 at 21:46:05 UT As a precaution, we note that the absolute photometric calibration may have been adversely affected by condensation in the cryostat window due to high humidity. Our high cadence q-band observations show a power-law decline with a temporal index of -1.2 throughout the observations. MeerLICHT is built and run by a consortium consisting of Radboud University, University of Cape Town, the South African Astronomical Observatory, the University of Oxford, the University of Manchester and the University of Amsterdam. View this GCN Circular online at https://gcn.nasa.gov/circulars/35323. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...