TITLE: GCN CIRCULAR NUMBER: 40333 SUBJECT: GRB 250502a: Liverpool Telescope optical follow-up DATE: 25/05/03 11:37:18 GMT FROM: A. Bochenek at Liverpool John Moores University a.m.bochenek@2023.ljmu.ac.uk
A. Bochenek and D. A. Perley (LJMU) report:
We observed the SVOM-detected GRB250502a (Wang et al., GCN 40313) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 6x100s exposures in the SDSS r’ filter starting at 2025-05-02 23:54:39 UT, approximately 15.28 hours after the trigger. The first exposure had to be discarded, due to a tracking error.
We report a detection in the stacked image at the position of the optical counterpart (Rakotondrainibe et al., GCN 40315; An et al., GCN 40319). The magnitude of the afterglow is r = 21.04 ± 0.05, which is in agreement with observations by de Ugarte Postigo et al. (GCN 40328) and Pérez-Fournon et al. (GCN 40330). The photometry was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction.
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