GCN Circular 44780

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

We observed the field of EP-WXT Trigger 01709266414 (presumably EP260602b) detected by Einstein Probe (EP), using the JinShan 100B and 100C telescopes 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) = 18:13:53.7 (273.4738 deg)
Dec. (J2000) = +07:34:16.4 (7.5712 deg)

with an uncertainty of ~ 1.0 arcsec. The source had r ~ 19.0 mag at a median time of ~ 1.0 hr post-trigger, calibrated with Pan-STARRS DR2 and not corrected for Galactic extinction of A_V ~ 0.94 mag. We thus think the source is the optical counterpart.

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