TITLE:   GCN CIRCULAR
NUMBER:  37134
SUBJECT: GRB240809A: Liverpool Telescope optical follow-up observations
DATE:    24/08/10 21:29:26 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 Gamma-Ray Burst GRB240809A (Evans et al. GCN 37110 ; Want et al. GCN37113) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 5x120s exposures with the SDSS-R and SDSS-I filters starting at 2024-08-09 21:48:46 UT, approximately 13.3 hours after the trigger.

The afterglow is detected in every exposure at a position consistent with previous detections reported by Dubay et al. (GCN 37114) and Jiang et al. (GCN 37116). The obtained results are given below:

MJD (mid)          T_mid - T_0       Filter      Mag. (AB)
60531.91279        13.40 h             r          20.54 ± 0.05
60531.18419        13.60 h             i          20.43 ± 0.05


The photometry was obtained using nearby PanSTARRS secondary standards and was not corrected for extinction.