TITLE:   GCN CIRCULAR
NUMBER:  40190
SUBJECT: GRB 250419A: Liverpool Telescope observations
DATE:    25/04/21 10:19:17 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 GRB250419a (Wang et al., GCN 40168) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 6x100s exposures in the SDSS r’ and i’ filters starting at 2025-04-20 21:43:22 UT, approximately 1.80 days after the trigger.
 
We report a detection in both bands at the position of the optical counterpart (López et al., GCN 40169; Xin et al., GCN 40170; Zheng et al., GCN 40171; Kumar et al., GCN 40172; Thakur et al., GCN 40174; Lipunov et al., GCN 40179; Odeh et al., GCN 40180; Perley et al., GCN 40181; Pankov et al., GCN 40182; Pérez-Fournon GCN 40183; Kuin et al., GCN 40185; WU et al., GCN 40186; Xie et al., GCN 40187, Jiang et al., GCN 40188, Ghosh et al., GCN 40189). The obtained magnitudes are r = 20.61 ± 0.09 and i = 20.41 ± 0.08. The photometry was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction.

MJD (mid)          T_mid-T_0        Filter       Mag. (AB)
60785.90925        43.33 h            r          20.61 ± 0.09
60785.91782        43.54 h            i          20.41 ± 0.08