Figure 39.

The isotropic component includes unresolved diffuse extragalactic emission, residual instrumental background, and possibly contributions from other Galactic components that have a roughly isotropic distribution. The spectrum has a dependence on the IEM and the ROI used for the calculation, as well as the data set. For the IG IEM (which uses the isotropic IC sky maps), we calculate the All-Sky (solid black line) isotropic component in the following region: |b| ⩾ 30°, 45° ⩽ l ⩾ 315°. We also calculate the isotropic component in the different sky regions as follows. North: b ⩾ 30°, 45° ⩽ l ⩽ 315° (orange dashed line). South: b ⩽ −30°, 45° ⩽ l ⩽ 315° (green dashed line). East: |b| ⩾ 30°, 180° ⩽ l ⩽ 315° (blue dashed line). West: |b| ⩾ 30°, 45° ⩽ l ⩽ 180° (purple dashed line). The calculations are performed using a log parabola (LP) scaling for the diffuse components. In addition, we calculate the isotropic spectrum at high latitudes (|b| ⩾ 50°), scaling just the normalizations of the diffuse components. The brown squares show the official FSSC isotropic spectrum (iso_P8R2_CLEAN_V6_v06). The gray band is our calculated isotropic component systematic uncertainty for the IG IEM, as shown in Figure 8.