[f. ASTRO- + Gr. μέτρον measure.] An instrument for measuring the apparent relative magnitude of the stars.
1830. in Edin. Encycl., II. 582.
1867–77. Chambers, Astron., 748. A useful astrometer, for determining star-magnitudes by the method of limiting-apertures, has been invented by Mr. E. B. Knobel.
