TITLE:   GCN CIRCULAR
NUMBER:  43081
SUBJECT: EP251212a: EP-FXT follow-up observation
DATE:    25/12/13 04:25:21 GMT
FROM:    EP Team at NAOC/CAS <ep_ta@bao.ac.cn>

J. Yang (ZZU), Y. H. Jiang (NJU), Z. X. Li, G. L. Huang, J. Y. Cao (IHEP), S. Y. Fu (HUST), Z. X. Ling (NAOC) on behalf of the Einstein Probe (EP) team:

EP-FXT performed a follow-up observation of EP251212a (GCN 43076) at 2025-12-12T13:44:09 (UTC), about 7.5 hours after the WXT detection, with an exposure time of 2.7 ks. FXT detected an uncatalogued source within the WXT error circle at R.A. = 134.0471, DEC = -23.2992 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic).  The FXT X-ray spectrum of this uncatalogued source can be fitted with an absorbed powerlaw with a hydrogen column density of 1.1 x 10^21 cm^-2 and a photon index of 1.7. The derived unabsorbed 0.5-10 keV flux is approximately 1.54 x 10^-12 erg/s/cm^2.

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).