from PSF0 to PSF3, the latter being the quartile with the best angular resolution (68% containment radius of 0.4° at 1 GeV compared to 0.8° without selection). This type of event selection, combined with the large amount of data collected by the LAT since its launch, makes Pass 8 $\gamma$ rays a powerful tool to identify and study extended $\gamma$-ray sources.

Data analysis\[sec:ata\]
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We perform a binned analysis using 6.5 years of data collected from August 4, 2008 to January 31, 2015, within a 10° $\times$ 10° region around the position of SNR G326.3$-$1.8. Since the object remains significant with $25\%$ of the data (more than 24$\sigma$ between 300 MeV and 300 GeV), we take advantage of the new PSF3 selection to limit contamination between the PWN and the SNR components as well as that from the Galactic plane. We select events between 300 MeV and 300 GeV, with a maximum zenith angle of 100° to reduce the contamination of the bright Earth limb. Time intervals during which the rocking angle of the satellite was more than 52° are excluded as well as those during which it passed through the South Atlantic Anomaly. We set the pixel size to 