GCN 44764: EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection

2026-06-02T10:23:04.250Z | rev 0 | event: EP260601a

X. Liu, Z.P. Zhu, D. Xu, J. An, S.Q. Jiang, L.B. He (NAOC), S.Y. Fu, A.D. Zhu, L. Lei (HUST), J.Z. Liu (XAO) report:

We observed the field of EP-WXT Trigger 01709266307 (EP260601a) detected by Einstein Probe (EP), using the JinShan 100B telescope located at Altay, Xinjiang, China. A series of r-band frames were obtained. 

An uncatalogued and decaying source is detected within the EP/WXT error circle at coordinates

R.A. (J2000) = 17:10:38.24
Dec. (J2000) = -01:38:42.4

with an uncertainty of ~ 1.0 arcsec. The source had r ~ 18.4 mag at a median time of ~ 0.73 hr post-trigger, calibrated with Pan-STARRS DR2 and not corrected for Galactic extinction of A_V ~ 1.15 mag. We thus think the source is the optical counterpart of EP260601a.

We also note the presence of a faint source with g ~ 25.2 mag in the Legacy Survey DR10 image at the above position, which could be the host of EP260601a.

We acknowledge the excellent support from T.Q. Chen, and J.F. Zhang for enabling these observations.