Top panel: simulation of a bright point-source with flux 10⁻¹¹ erg s⁻¹ cm⁻² in a four-year eROSITA equatorial region (∼2 ks exposure time). The image shows the sky projection of the 0.5–2 keV source events collected by the seven CCD, binned with 4″ pixels. Left: “Survey PSF”, including all events. Middle: selecting only low off-axis events (θ < 16.5′, 40% of the total number of events). Right: selecting only large off-axis events (θ > 16.5′, 60%). The circle has a radius of 30″, slightly larger than the half-energy width of the survey PSF. Bottom panel: corresponding radial profiles in 4″ bins (error bars are only shown for the top curve).