Assertion: telescope's aberration | /r/HasProperty | mounted inside the focusser tube
Facets:
value: in front of the secondary mirror
type: LOCATION
value: usually
type: TEMPORAL
Source sentences:
text: The design uses a spherical primary mirror in place of a parabolic one, with spherical aberrations corrected by sub-aperture corrector lens usually mounted inside the focusser tube or in front of the secondary mirror.