TITLE:   GCN CIRCULAR
NUMBER:  44639
SUBJECT: EP260514a: TRT optical counterpart candidate
DATE:    26/05/16 07:39:15 GMT
FROM:    liuxing@nao.cas.cn

X. Liu, (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan, K. Noysena, K. Chanchaiworawit (NARIT), S.Q. Jiang, J. An, Z.P. Zhu, L.B. He, D. Xu, Z. Fan, W.X. Li, N.C. Sun (NAOC), S.Y. Fu (HUST) report:

We observed the field of EP260514a dtected by EP/WXT (Cheng et al., GCN 44613; Lipunov et al., GCN 44614; Mohan et al., GCN 44619; Sánchez et al., GCN 44632; Li et al., GCN 44638), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Fresno, California, U.S.A (SRO). Observation started at 2026-05-15 04:25:07 UT, i.e., 0.48 day post-burst, and 6x300 s R-band frames were obtained. 

Image subtraction using Legacy-DR10 reveals an uncatalogued optical source within the EP/WXT (Cheng et al., GCN 44613) error circle at coordinates
R.A. (J2000) = 14:17:10.41
Dec. (J2000) = +49:22:30.9

with an uncertainty of ~ 1.5 arcsec. The source had R ~ 21.8 mag with SNR of ~3 at a median time of 11.74 hrs post-trigger, calibrated with Pan-STARRS DR2 converted using Lupton (2005) equations and not corrected for Galactic extinction.

The magnitude is consistent with those reported by SVOM/VT (Li et al., GCN 44638). No NEO would be at the above position at the observational time by checking MPC.

We think the source could be the optical cointerpart of EP260514a.