Any of various instruments for measuring parameters relating to celestial objects, esp. their apparent magnitude or apparent diameter.

= astrometer, n.

Any of various instruments for measuring the intensity of scintillation (scintillation, n. 2).

an instrument for measuring the brightness of a star's light.

A flat mirror mounted and slowly rotated to compensate for the diurnal rotation of the celestial sphere, so that light from a celestial object under…

an instrument consisting of a wedge of glass, used for measuring the comparative brightness of stars.

Astronomy. An instrument for examining the scintillation of stars. Cf. scintillometer, n. 2. Obsolete. rare.