Statistical significance (left) and excess (center) maps in a region of 2° ×2° around LHAASO J2108+5157 in the range of energy between 3 TeV and 100 TeV. The map was produced using the Gammapy tool for the ring-background model: the OFF region is defined as a 0.3° radius ring, with a width of 0.3°, around a 0.2° radius circular ON region. The correlation radius for the building of the maps was fixed at 0.2° according to the value of the PSF (68% containment) in this range of energy, averaged for the different zenith bins used for the production of the IRFs. The same exclusion region was used as that adopted to build the acceptance model. Right: Significance distribution for the off bins (purple) and for all bins (pink). The black line represents a Gaussian fit of the background, providing the mean value μ = −0.03, and standard deviation σ = 1.15.