20 minutes exposure, Kodak Elitechrome 200 slide film.
5" f/5 refractor, prime focus.
The brighter stars in the constellation Coma Berenices have long been suspected of forming a loose open cluster. However it is far from certain if they are actually accociated with each other. Burnham gives the radial and proper motions for many of these stars and leaves it to his readers to draw their own conclusions.