he CGEM 800 HD combines Celestron s newly designed CGEM Computerized Equatorial mount with its new EdgeHD optical system. With over 8 inches of aperture and our premium StarBright XLT coatings, the CGEM 800 HD gives you over 800 times the light gathering power than the unaided eye. Supporting an optical tube of only 13 lbs, the CGEM 800 HD is the lightest and most portable in its class.