TITLE: GCN CIRCULAR NUMBER: 39456 SUBJECT: GRB 250219A: EP-FXT afterglow detection DATE: 25/02/24 14:43:44 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com> D. Turpin (CEA), P. Y. Han, C. X. Zhang (HUST), J. Yang (NJU), X. Tian (GXU), D. F. Hu (PMO, CAS), W. Chen (NAO, CAS), J. Guan, C. K. Li, Y . Chen, S. M. Jia, W. W. Cui, D. W. Han, W. Li, C. Z. Liu, F . J. Lu, L. M. Song, J. Wang, J. J. Xu, J. Zhang, S. N. Zhang, H. S. Zhao, X. F . Zhao (IHEP , CAS), Y . Liu, C. C. Jin, C. Zhang, Z. X. Ling (NAOC,CAS), B. Cordier (CEA) on behalf of the SVOM and Einstein Probe teams We performed a follow-up observation of GRB 250219A (Daigne et al., GCN 39376) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation started at 2025-02-21T07:04:16 (T-TGRB ~ 1.63 days) for about 3ks of exposure in total. An uncatalogued X-ray source is detected by both FXT-A and FXT-B at the position of the x-ray afterglow candidate reported by Swift/XRT (Kennea et al., GCN 39379). This position is also consistent with the optical afterglow detected by SVOM/VT (Xin et al., GCN 39380), COLIBRÍ (Magnani et al. GCN 39382) and the NOT (Fu et al., GCN 39383). A preliminary analysis shows that the spectrum can be fitted with an absorbed power law with nH=1.53*10^20 cm^-2 and a photon index of 1.53 (-0.68/+0.70) . The observed flux in the 0.3-10.0 keV is 4.4 (+2.2/-1.1)*10^-13 erg/s/cm^2. Compared to the Swift/XRT epoch Kennea et al., GCN 39379), the observed source flux has faded by almost one order of magnitude with a temporal slope alpha~-0.56. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/39456. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...