What typical magnifications did 19th-century observational astronomers use for lunar and planetary viewing?
CLYDE BOYER, SPRING CREEK, NEVADA
Observers often used the large refractors built in the 19th century for planetary observations. Through large telescopes like the Lick 36-inch refractor, the 26-inch U.S. Naval Observatory (USNO) refractor, and the 40-inch Yerkes Observatory refractor, magnifications of 400x to 600x were not uncommon. On nights when the seeing could be described only as "legendary," magnifications of 750x, 1,000x, and higher occasionally were employed.