Assertion: chrétien telescope | /r/HasProperty | invented by henri chrétien
Facets:
value: in the early 1910s
type: TEMPORAL
Source sentences:
text: The Ritchey–Chrétien telescope, invented by George Willis Ritchey and Henri Chrétien in the early 1910s, is a specialized Cassegrain reflector which has two hyperbolic mirrors (instead of a parabolic primary).