Fermi-LAT SED of SrcX1 (black dots) and SrcX2 (blue dots), with arrows indicating the 95% upper limits. Red dots represent the HESS observation of HESS J1858+020 (Aharonian et al. 2008). Gray butterfly indicates the best-fit power-law of SrcX1 in the energy range of 1–500 GeV. Solid green line is the joint fit for the Fermi-LAT data of SrcX2 and HESS data of HESS J1858+020. The cyan dotted and dot-dashed lines show the differential sensitivities of LHAASO (1 yr) with different sizes of photomultiplier tube (PMT; Bai et al. 2019). Black dotted line represents the differential sensitivity of CTA-North (50 h; CTA Consortium 2019).