What are drive systems for modern astronomical telescopes?
Instead of turning mounts manually, they can be driven automatically. And although normally electrically driven, more sophisticated computer drives are now available.
What is the apparent magnitude of a star?
Apparent magnitude is the apparent brightness of a star as seen from Earth. Star magnitudes are denoted by numbers 1 to 6 where 1 refers to the brightest stars and 6 to the faintest star visible to the unaided eye. The scale is logarithmic. Hence magnitude 2 stars are 2.512 times fainter than magnitude 1 stars. Magnitude 3 stars are 6.310 times fainter than magnitude 1 stars.
Celestial objects brighter than magnitude one may have zero or negative magnitude. Celestial objects fainter than magnitude six may have higher values of magnitude. The lower the apparent magnitude, the brighter is the star.
What is the absolute magnitude of a star?
The absolute magnitude of a star is a hypothetical concept and is the apparent magnitude the star would have if it were located at a standard distance of 10 parsecs from the Earth.
The absolute magnitudes of stars provide a measure of their relative luminosities, by comparing the apparent brightness which stars would have if they all lay at the same distance. If the Sun was at a distance of 10 parsecs, it would be a faint star of absolute magnitude +4.8.