GCN Circular 38586

H. Zhou (PMO, CAS), R. D. Liang (NAO, CAS), S.-F. Zhu (USTC), Z. X. Ling (NAO, CAS) report on behalf of the Einstein Probe team:

We report on the detection of an X-ray transient by the Einstein Probe (EP), designated as EP241217a (Trigger ID: 01709129076). The source triggered the on-board processing unit of the Wide-field X-ray Telescope (WXT) at 2024-12-17T05:36:03 (UTC). The WXT position of the transient is R.A. = 46.957 deg, Dec. = 30.901 deg, with an uncertainty of 2.8 arcmin (90%). No previously known bright X-ray sources are found within the error circle around the transient position.

The Follow-up X-ray Telescope (FXT) onborad EP performed an autonomous follow-up observation and found an uncatalogued X-ray source, located at R.A., Dec. = 46.9398, 30.9299 deg with an uncertainty of about 20 arcsec (90%). More information will be updated when the telemetry data is received. The ZTF and PANSTARR images show there are one point source and an extended source within the 90% unceratinty of the localization, and the distances to the FXT position are about 18.9" and 9.7", respectively. Further observations are encouraged to explore the origin of EP241217a.

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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.