GCN Circular 43888
R. A. J. Eyles-Ferris (Leicester), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud), and J. Chacón (PUC) report on behalf of a larger collaboration:
We observed the optical counterpart of the fast X-ray transient EP260227a (Wang et al., GCN 43869) with an LCO 1m telescope located at the Cerro Tololo Inter-American Observatory (Chile) equipped with the SINISTRO instrument. We obtained nine 300 s exposures in the r band from 2026-03-01 07:52:01 to 2026-03-01 08:43:10 UT (t_mid = 36.09 hr).
In our stacked image, we clearly detect the optical counterpart (Eyles-Ferris et al., GCN 43867; Li et al., GCN 43868; Fu et al, GCN 43873; Mandarakas et al., GCN 43874; Eyles-Ferris and Tanvir et al., GCN 43875; Malesani et al., GCN 43876; Eyles-Ferris et al., GCN 43877; Strausbaugh et al., GCN 43879; Bochenek et al., GCN 43880; Gassert et al., GCN 43881; Gupta et al., GCN 43884; Ma et al., GCN 43887). We measure an AB magnitude of r = 22.82 +/- 0.28 calibrated to Pan-STARRS and not corrected for Galactic extinction.
Our observations suggest there is no significant evolution since the observations of Gupta et al. (GCN 43884) ~12 hr earlier.