TITLE:   GCN CIRCULAR
NUMBER:  43332
SUBJECT: EP260105a: LCO Optical Upper limit
DATE:    26/01/05 11:05:43 GMT
FROM:    Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo@ucd.ie>

G. Corcoran (UCD), J. Quirola-Vasquez (Radboud), F. E. Bauer (SSI and UTA), A. Levan (Radboud), A. Martin-Carrillo (UCD), P.G. Jonker (Radboud) report on behalf of a larger collaboration:

We observed the field of the fast X-ray transient EP260105a (Zhou et al. GCN 43327) using the Las Cumbres Observatory (LCO) network at the Cerro Tololo Inter-American Observatory node using the Sinistro instrument on the 1m telescope. A series of 6x300s exposures were taken in the SDSS-r filter starting at 2026-01-05T07:10:04.556 UTC (1.326 hours after the WXT trigger).

We do not detect any sources within the EP/FXT uncertainty region. From the stacked image we obtain a 3 sigma upper limit of:

r > 21.5.

This upper limit is in AB magnitudes, was calibrated using nearby stars from the Pan-STARRS catalog and is not corrected for Galactic extinction. Our observations are consistent with the upper limits reported by Lipunov et al. GCN 43328.