GCN Circular 44207
Subject
EP260403a: LCO optical counterpart detection
Event
Date
2026-04-03T13:19:20Z (10 hours ago)
Edited On
2026-04-03T15:35:48Z (8 hours ago)
From
Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>
Via
Web form
I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz,
I. Correa-Plasencia, E. Lekaroz-Urriza, M. Quintana-Ansaldo (all ULL), A. López-Oramas (IAC and ULL), and D. Aguado (IAC and ULL)
Following the detection of the fast X-ray transient EP260403a (Guo et al., GCN circ. 44204) by the Wide-field X-ray Telescope (WXT) and the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission, we observed the field with one of the two Las Cumbres Observatory (LCO) 1-m telescopes equipped with Sinistro cameras located at the LCO node at Siding Spring Observatory near Coonabarabran, New South Wales, Australia. The observation, a single exposure of 180 sec in the SDSS r' filter, started on 2026-04-03 at 11:28:01 UT, about 58.8 minutes after the EP WXT trigger. The optical counterpart, first reported by Antier et al. (GCN circ. 44206), is detected in our image with an AB magnitude of r' = 19.09 +/- 0.21, calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction.
This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2026A-011, SGLF and Superluminous Supernovae surveys).
This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5).