The half energy width (angle over which half the energy is deposited) is around 16 arcsec on the axis of the telescopes (3600 arcsec=1 deg). Due to the Wolter g

The half energy width (angle over which half the energy is deposited) is around 16 arcsec on the axis of the telescopes (3600 arcsec=1 deg). Due to the Wolter geometry, it gets worse as you go off-axis. In the survey sources scan over the field of view. The average survey performance is around 28 arcsec.