GCN Circular 43390

Subject

EP260110a: TRT optical upper limits

Event

EP260110a

Date

2026-01-13T16:28:35Z (3 days ago)

Edited On

2026-01-13T16:39:05Z (3 days ago)

From

Zipei Zhu at NAOC <zpzhu@nao.cas.cn>

Edited By

Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Zipei Zhu at NAOC <zpzhu@nao.cas.cn>

Via

Web form

Z.P. Zhu (NAOC), S. Tinyanont, K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), J. An, X. Liu, S.Q. Jiang, L.B. He, N.C. Sun, W.X. Li, D. Xu (NAOC), S.Y. Fu (HUST) report on behalf of a large collaboration:

We observed the field of EP260110a detected by the Einstein Probe (EP) (Zhang et al., GCN 43363

), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Sierra Remote Observatories in California. We obtained several 360 s frames in the R filter. Observations started at 07:38:55 UTC on 2026-01-11, i.e., 0.44 day after the EP/WXT trigger time.

No new source is detected within or at the border of the EP/FXT error region (Zhang et al., GCN 43367

), being consistent with the non-detection reported at other telescopes (Perez-Garcia et al., GCN ; Kang et al., GCN ; Antier et al., GCN ; Zheng et al., GCN ; Lipunov et al., GCN ; Li et al., GCN ). From the stacked images we obtain the following 5-sigma upper limits in Vega magnitude:

Mid-time(d)	filter	upper limit	site
0.46	R	> 19.6	SRO
1.45	R	> 20.9	SRO
2.44	R	> 21.0	SRO

calibrated using nearby stars from the Pan-STARRS DR1 catalog and are not corrected for Galactic extinction.