GCN Circular 43805
Subject
EP260221a: Gemini South z-band upper limit
Event
Date
2026-02-22T11:42:57Z (10 days ago)
From
Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo@ucd.ie>
Via
Web form
Andrew J. Levan (Radboud), G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), J. A. Quirola-Vasquez (Radboud), R. A. J. Eyles-Ferris (Leicester), J. Sanchez-Sierras (Radboud), D. Xu (NAOAC), report on behalf of a larger collaboration
We observed the field of the fast X-ray transient EP260221a (Zhang et al., GCN 43791; Liu et al., GCN 43802) using the GMOS-S instrument mounted on the Gemini South telescope (Cerro Pachon, Chile). A single 300 s z-band observation was secured starting on 2026 Feb 22 at 08:20 UT (20.62 hr after trigger).
No new source is detected within the EP/FXT error circle, down to a limiting magnitude z = 24.8 (AB, calibrated against nearby sources from the Pan-STARRS catalog, and not corrected for Galactic extinction). A number of faint sources are visible consistent with the EP/FXT position, but they are all present in archival imaging from the Legacy survey and from DECam.
Our results are consistent with other non-detection reports (Mandarakas et al., GCN 43793; Kumar et al., GCN 43794; He et al., GCN 43798; Lipunov et al., GCN 43803).
We thank excellent support from the Gemini staff, in particular Lindsay Magill.