Left panel: PS map of the RoI. The gradient represents positive and negative residuals in the RoI, rescaled in terms of statistical significance according to the definition in Bruel (2021). Negative values imply an overestimation of the background. The Galactic plane is highlighted with a dashed line. In the inset, the white cross shows the position of our source, included in the model and therefore blended with the background. Right panel: histogram of the PS values in units of standard deviations, derived from the joint weighted likelihood fit that includes the source under examination in the spectral model. Negative values correspond to areas where the model overestimates the background, and positive values areas where the model underestimates it.