GCN Circular 45650

Subject

EP260920a: LCO optical counterpart candidate

Event

EP260920a

Date

2026-09-20T02:33:40Z (2 days ago)

From

liuxing@nao.cas.cn

Via

Web form


X. Liu, D. Xu, J. An, Z. Fan, J.F. Gou, L.B. He, Y.L. Hua, S.Q. Jiang, W.X. Li, R.D. Liang, Q. Zhao, Z.P. Zhu (NAOC), Y.L. Hua (PMO), S.Y. Fu, L. Lei (HUST) report:

We observed the field of EP260920a triggered by Einstein Probe (EP; Ni et al., GCN 45649Loading...
 
 ), using an LCO 1m telescope network. We obtained 3 x 200 s exposures in the w filter.

A residual optical transient (OT) is detected at coordinates

R.A. (J2000) = 01:46:06.71
Dec. (J2000) = -13:59:06.1 

after subtracting the archival Legacy Survey image, which is within the EP-FXT error circle (EP; Ni et al., GCN 45649Loading...
 
 ). There is a known source at the above coordinates, which has g = 23.39, r = 22.02, i = 20.68, and z = 20.14, and is classified as Point-like in Legacy Survey. The OT and the known source together has r ~ 21.67 mag in the LCO stacked image at a median time of ~1.174 hr post-trigger, and the OT was decaying in the LCO three images.

We thus think the above OT/known source could be optical counterpart of EP260920a.