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(Astronomy) a form of reflecting astronomical telescope with a concave ellipsoidal secondary mirror and the eyepiece set behind the centre of the parabolic primary mirror
[C18: named after J. Gregory (died 1675), Scottish mathematician who invented it]
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|Noun||1.||Gregorian telescope - a reflecting telescope that has a paraboloidal primary mirror and a hyperboloidal secondary mirror; light is brought to a focus through an aperture in the center of the primary mirror|