M57 (NGC6720) Ring Nebula

July 18, 2003  3:13am ~ 4:07am EST
University of Maryland Observatory, College Park, MD USA

Celestron 14" Schmidt-Cassegrain Reflector f/11
SBIG ST-8 CCD Camera, Bessel V filter
10 x 35sec. + 1 x 50sec. + 2 x 60sec. exposures combined(using Add) by AstroStack 2.1.0, false color