Assertion: telescope's mirror | /r/CapableOf | provide long focal length path
Facets:
Source sentences:
text: These are a) the prime focus, where the detector is simply placed at the prime focus of the mirror; b) the Newtonian, where a small, flat mirror reflects the light out to the side of the telescope; c) the Cassegrain, where the focus is located behind the plane of the primary mirror through a hole in its center and d) the Coudè, where the two flat mirrors provide a long focal length path as shown.