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How Faint Can You See ? Test your Limiting Magnitude

Basic procedure ( see article in Sky & Telescope ) : Keep your eye at the eyepiece for at least 5 - 10 minutes and try to hold your eye still for periods of 50 - 100 seconds at a fixed point in the eyepiece in order to reach the 5% probability level ( + 1.5 mag ) or better. You may then glimpse the target star for a short moment. For 8" - 10" telescopes with lim mag 14, this should be mag 15.5
Try a 12" telescope under dark sky on the mag 15.9 star close to and under the center of the image.

Image show stars with visual magnitudes based on chart prepared by the late Edgar Everhart.
The arrow points to a 18.7 magnitude star seen by Barbara Wilson, John Bortle and Stephen O'Meara using a 20" telescope at the 1991 Texas Star Party.

The bright star SAO 82672 ( mag 8 ) is at 13h 08m 38.7s +29° 23' 00" ( J2000 ). Field approx. 12'

ref. article by Roger N. Clark Sky & Telescope April 1994 p. 106




Other test charts. See Roger Clark's Visual Astronomy of the Deep Sky



Area M57 ( not 51 )



Ref. to image