GRB 241113B: EP-FXT afterglow detection

We performed a follow-up observation of GRB 241113B (SVOM/ECLAIRs, Dagoneau et al., GCN 38196; SVOM/GRM, Liu et al., GCN 38212; EP/WXT, Liu et al. GCN 38214) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation started at 2024-11-13T15:43:11 (T-TGRB ~ 4.3hr) for about 3ks of exposure in total. An uncatalogued X-ray source is detected by both FXT-A and FXT-B at the position (J2000) RA, DEC = 110.2396, 46.787 (error=10", 90% C.L.), 1.09 arcminute away from the SVOM/ECLAIRs position (Dagoneau et al., GCN 38196). This position is also consistent with the optical afterglow detected by KAIT (Zheng et al., GCN 38232) and SVOM/VT (Qiu et al., GCN 38306). A preliminary analysis shows that the spectrum can be fitted with an absorbed power law with nH=0.72*10^21 cm^-2 and the photon index of 2.11. The observed flux in the 0.5-10.0 keV is 1.7(-0.4/+0.4)*10^-13 erg/s/cm^2. The above observation was made with the EP-FXT instrument. 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.