Exploration of SEDs and SBPs of HESS J1813-126 in the 2ZISD framework. Left: SEDs corresponding to different choices of inner zone diffusion coefficients. The D₀ in the plot signifies the normalization of the inner zone diffusion coefficient. Middle: Angle-integrated SEDs with increasing aperture sizes starting from 0.34°, assuming D₀ = 5 × 10²⁷ cm² s⁻¹. In these two panels, the brown squares and green triangles (along with the upper limits) correspond to the off-pulse emission from Ackermann et al. (2011) and this work (PS J1813.3-1246), respectively. The blue data points and butterfly plot correspond to the H.E.S.S. data, whereas the purple, pink, and sky blue butterfly plots correspond to the HAWC, LHAASO WCDA, and KM2A observations, respectively. We also provide the sensitivity curves for the CTA-North (gray), CTA-South (yellow-green), and SWGO (red) for comparison. Right: SBPs for three different energy ranges scaled to start from the same point. Vertical lines correspond to the aperture sizes and have the same color scheme as in the middle panel.