An apparatus for observing the sun without injury to the eye, or a telescope fitted with such an apparatus; the intensity of the light being reduced…

An apparatus consisting of a mirror turned by clockwork so as to reflect the light of the sun in a fixed direction. (Also applied to a simpler…

A photographic telescope for photographing the sun; = heliograph, n. 2.

= photoheliograph, n.

An instrument for photographing the sun's corona in full sunlight; also, a telescope for observing the sun's corona.

(a) an instrument which photographs the sun using light of a particular wavelength, esp. that of the Balmer α emission line of hydrogen; †(b) a…

an instrument which provides a directly observable monochromatic image of the sun by means of a rapidly scanning device which transmits light of…

a spectrophotometer for use in studying the sun.