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GCN Circular 43698

Subject
EP260209a: LCO optical upper limits
Event
EP260209a
Date
2026-02-11T16:41:01Z (a day ago)
From
Gregory Corcoran at University College Dublin <gregory.corcoran@ucdconnect.ie>
Via
Web form
G. Corcoran (UCD) and J. A. Quirola-Vasquez (Radboud) report on behalf of a larger collaboration:

We observed the field of the fast X-ray transient EP260209a (Zhang et al., GCN 43693) using the LCO 1m telescope located at the McDonald Observatory (Texas, USA) equipped with the SINISTRO instrument. Our observations consisted of a sequence of 4x300 s exposures in the SDSS r-band starting on 2026-02-11 at 12:22:56 UT (~1.44 days after the WXT trigger).

We do not detect any sources within the EP/FXT uncertainty region (Zhang et al., GCN 43693). From the stacked image, we obtain the following 3-sigma upper limiting magnitude:


r > 22.5

This limit is in the AB system, calibrated using nearby stars from the Pan-STARRS catalog, and not corrected for Galactic extinction.
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