GCN Circular 41568
Subject
EP250827a: confirmation of optical rebrightening with LCO
Event
Date
2025-08-27T18:04:37Z (a month ago)
From
Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>
Via
Web form
I. Pérez-Fournon, F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz, I. Correa-Plasencia (ULL), and A. López-Oramas (IAC and ULL)
We observed the field of EP250827a, detected by Einstein Probe (Hua et al. GCN 41553) and Swift-XRT
(Evans et al. GCN 41563) at a redshift of z = 1.613 (Levan et al. GCN 41557) with one of the three 1-m telescopes of the Las Cumbres Observatory Global Telescope network (LCO) equipped with Sinistro cameras located at the LCO node at the Cerro Tololo Inter-American Observatory (CTIO), Chile. The observation, of 300 seconds in the SDSS-r filter, started at 2025-08-27 10:04:04 UT, about 2.39 hours after the EP trigger. We detect clearly a source within the EP-FXT and Swift-XRT error circles at a position consistent with the detections reported by Levan et al. (GCN 41554) and Li et al. (GCN 41555) and with other optical detections reported by Lipunov et al., GCN 41558; Gritsevich et al., GCN 41559; An et al., GCN 41560, Ghosh et al., GCN 41564; and O'Neill GCN 41567). We measure a magnitude of r = 18.65 +/- 0.04, calibrated with the Legacy Surveys DR10 catalog and not corrected for Galactic extinction. Using a similar r-band filter, we confirm the optical rebrightening detected also by Ghosh et al. (GCN 41564) between the TRT observation (r = 18.93 +/- 0.03, 0.86 hours after the EP trigger) and our LCO observation (r = 18.65 +/- 0.04, 2.39 hours after the EP trigger).
This work makes use of observations from the Las Cumbres Observatory global telescope network program IAC2025B-008 (SGLF).