GCN Circular 38554

X.-Y. Zhou (PRIC), R.-Z. Li (YNAO, CAS), D.-F. Hu (PMO, CAS), S.-X. Wen, H.-W. Pan (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 EP241213a. The source was first detected by the Wide-field X-ray Telescope (WXT) on board EP in a single pointing observation (with an exposure time of 1.6 ks) at 2024-12-13T02:17:15 (UTC). The position of the transient is R.A. = 116.182 deg, Dec. = 35.271 deg, with an uncertainty of 2.8 arcmin. No previously known bright X-ray sources are found within the error circle around the transient position.

The WXT spectrum of the observation can be fitted by an absorbed power law with a photon index of 2.2+/-1.4, with the NH of (5.9+/-4.8) e21 cm^-2. The derived absorbed flux in 0.5-4 keV is ~5.2e-11 ergs/s/cm^2.

A Swift-XRT ToO proposal was submitted to observe the transient. Multi-wavelength follow-up observaitons are encouraged.

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.