Model sky maps of the Geminga X-ray halo flux coming from synchrotron emission as integrated in the 8−40 keV band, and overlaid with the NuSTAR FoVs for the focused and stray-light X-ray photon components for a squared region of 10 × 10° (left panel) and the central 1 × 1° (right panel). The central 13′×13′ green squared region around the Geminga pulsar (red circle) will be focused through the NuSTAR optics, while X-rays within r ∼ 1 − 4° region around the target (unshaded area in the left panel, for module A; see also Fig. A.2) will be detected as stray-light photons. The circular regions 1, 2 and 3 as defined in Section 3.2.1 are also shown in the right panel.