GCN Circular 41732

Subject

EP250905a: JinShan likely optical counterpart detection

Event

EP250905a

Date

2025-09-06T01:19:57Z (a month ago)

Edited On

2025-09-08T14:02:39Z (a month ago)

From

Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

Edited By

Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

Via

Web form


L.B. He, X. Liu, J. An, D. Xu, S.Q. Jiang, Z.P. Zhu (NAOC), S.Y. Fu (HUST), J.Z. Liu (XAO) report on behalf of a large collaboration:

We observed the field of EP250905a detected by Einstein Probe (Cheng et al., GCN 41725Loading...
 
 ), using the 100C telescope of the JinShan project, located at Altay, Xinjiang, China. We obtained 40 x 180 s Sloan i-band frames, starting from  2025-09-05 13:56:23 UT, i.e., 2.74 hrs since the EP trigger.

A new source is detected positionally in a known GLADE galaxy (GLADE+ #2980788) via image subtraction, which is within the EP-FXT 20-arcsec error circle , at coordinates

R.A. (J2000) = 0:17:48.01
Dec. (J2000) = +37:28:19.44

with an uncertainty of ~ 0.6 arcsec. The source has i ~ 22.9 mag, calibrated with PanSTARRS. 

We think the source is very likely the counterpart of EP250905a. In this case, the galaxy is the host with a redshfit of z ~ 0.28 from GLADE.

Further observations are planned and encouraged.