source extension is expressed in terms of the test statistic TS$_{\rm ext}$, where the hypothesis of the best-fit extended spatial model is tested against the null hypothesis of the best-fit point-like source. Given that in both hypotheses the localization of the source is optimized, the extended source model adds one degree of freedom – the source size – with respect to the point-source model. Thus, the significance can be directly interpreted as the square root $\sqrt{\rm{TS_{ext}}}$. As reported in Table \[tab:Fit\_Pointlike\], the $\gamma$-ray emission is extended with more than 13$\sigma$ confidence level and the uniform disk radius is found to be $r$ = $0.266^\circ$ $\pm$ 0.012$^\circ$. Figure \[fig:Best\_Disk\_Gaussian\] (left) shows the best-fit position and extension (68% containment radius $r_{68}$) for the disk and the Gaussian, plotted on the radio image, with the associated uncertainties. The centroid of each extended model is slightly shifted toward the radio PWN but is not coincident with its position. No significant residual emission appears in the residual TS map (not shown here) including either the disk or the Gaussian in the model.

[l|ccccccc]{}

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Spatial model & RA$_{\rm{J2000}}$ ($^\circ$)& Dec$_{\rm{J2000}}$ ($^\circ$) & $r$ or $\sigma$ ($^\circ$) & $r_{68}$ ($^\circ$) & TS & TS$_{\rm ext}$\

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