GCN Circular 44810
Subject
EP260602a: Liverpool Telescope optical upper limits
Event
Date
2026-06-03T19:58:47Z (3 months ago)
Edited On
2026-06-04T14:17:19Z (3 months ago)
From
A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>
Via
Web form
A. Bochenek, D. A. Perley, J. L. Wise (LJMU), report:
We observed the field of EP260602a (Li et al., GCN 44770) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained multiple 120s exposures in SDSS gri filters, starting at 2026-06-02 21:15:26 UT, approximately 13.07 hours after trigger. The observations were interrupted and consequently resumed due to weather conditions and telescope tracking issues; some exposures needed to be discarded.
We do not detect any sources at the position of the counterpart (Xu et al., GCN 44781, Li et al., GCN 44794; also Watson et al., GCN 44790; He et al., GCN 44798, Malesani et al., GCN 44807) down to the 3 sigma limiting magnitudes of:
| MJD (mid) | T_mid-T_0 | Exp. Time | Filter | Mag limit. (AB) |
| ------------ | ------------ | ------------ | ------------ | --------------- |
| 61193.93925 | 14.34 h | 600 s | g | > 21.8 |
| 61193.91413 | 13.75 h | 960 s | r | > 22.1 |
| 61194.11373 | 18.54 h | 720 s | i | > 21.9 |
The stacked exposures were subtracted from PanSTARRS reference imaging using custom PSF-matching image subtraction code utilising Swarp, SourceExtractor, and PSFex. The photometry is in the AB magnitude system, was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction.