GCN Circular 45234
Subject
The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
Event
Date
2026-07-28T01:53:54Z (a month ago)
From
L. B. He at NAOC <helb@bao.ac.cn>
Via
Web form
L.B. He (NAOC), S.Y. Fu (HUST), Z.P. Zhu, J. An, X. Liu, S.Q. Jiang, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), R.H. Rasmussen, O. Stalder (NOT) report:
We observed the field of EP-WXT trigger ID 01709276927 detected by EP using the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observation started at 2026-07-28T00:19:16.548 UT, i.e., 3.69 hrs post-burst, and a series of Sloan r- and z-band frames were obtained.
A brightened source was detected within the EP/WXT error circle at coordinates
R.A. (J2000) = 23:05:50.65 (346.46104)
Dec. (J2000) = +03:11:38.65 (3.19407)
with an uncertainty of ~ 0.5 arcsec. The source had r = 21.98 +/- 0.08 mag at a median time of 4.18 hrs post-trigger, calibrated with Pan-STARRS DR2 and not corrected for Galactic extinction.
We note that there is a faint source at that position in the Legacy Survey DR10 images with r = 23.73 +/- 0.23 and z_phot = 1.03 +/- 0.24.
No NEO was at the above position at the observational time according to MPC.
We thus think the source is likely the optical counterpart.