TITLE:   GCN CIRCULAR
NUMBER:  45321
SUBJECT: EP260809a: Einstein Probe detection of an X-ray transient
DATE:    26/08/09 02:46:04 GMT
FROM:    EP Team at NAOC/CAS <ep_ta@bao.ac.cn>

X. X. Sun(NAO, CAS), Q. J. Huang (PMO, CAS), K. J. Zhang(YNU), J. P. Chen (SYSU), Z. X. Ling(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 EP260809a. The transient triggered EP-WXT (ID: 01709277768) at 2026-08-09T00:38:56 (UTC). The WXT position of the source is R.A. = 328.573 deg, DEC = 17.607 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. = 328.5816 deg, DEC = 17.6072 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.

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).