TITLE:   GCN CIRCULAR
NUMBER:  40700
SUBJECT: EP250612a: Einstein Probe detection of an X-ray transient
DATE:    25/06/12 13:03:13 GMT
FROM:    EP Team at NAOC/CAS <ep_ta@bao.ac.cn>

Y. L. Hua (PMO, CAS), T. Zhao, Y. J. Song, J. W. Hu , W. Yuan (NAO, CAS) on behalf of the Einstein Probe (EP) team:

We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250612a. The transient triggered EP-WXT (ID: 01709178580) at 2025-06-12T12:28:05 (UTC). The WXT position of the source is R.A. = 229.654 deg, DEC = -26.757 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic).

A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 229.6503 deg, DEC = -26.7661 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic).

Further information will be updated when the telemetry data is received. 

The contact TA of EP250612a is Y. L. Hua, please contact him via email ylhua@pmo.ac.cn if needed. 

Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).