of the source, the Galactic and isotropic diffuse emissions are let free while the spectral parameters of the other sources are fixed to their best-fit values. Figure \[fig:Best\_Disk\_Gaussian\] (right) depicts the results of the fitting procedure in the individual energy bands. At low energies (300 MeV – 1 GeV), the PSF ($r_{68}$ $\sim$ 0.4$^{\circ}$ at 1 GeV) is larger than the SNR radius. An extended source of the SNR size is compatible with the data but is not significantly better than a point source. The associated best-fit position lies outside the radio PWN. Between $1$ and $3$ GeV, the significance of the extension is more than 5$\sigma$ (the values are reported in Figure \[fig:TS\_and\_TSext\]) and the position of the Gaussian appears to be fairly consistent with the center of the radio SNR. At higher energies (from 3 to 30 GeV), the $\gamma$-ray morphology is still significantly extended (more than 5$\sigma$) and the centroid of the best-fit Gaussian gets closer to the radio PWN. Above 30 GeV, the $\gamma$-ray emission is not significantly extended and the best-fit position lies inside the radio PWN.

### Building a more detailed model

This energy-dependent source morphology clearly requires a more detailed investigation beyond a 