Illustration of the fiducial volume chosen for the calculation of the expected detection and event rates. Only objects located in the red shaded area are taken into account. Specifically, all objects in a distance of D < 2 kpc are assumed to be visible. Any objects at a distance D > 25 kpc are assumed to be undetectable. Objects located in the disc are discounted by the assumption that objects with a Galactic latitude α < b < −α are invisible, with α = 10°. Earth’s position is as indicated. Illustration not to scale.