Astronomy Picture of the Day . ... 1.02.1999 . ... The gray building housing Subaru is visible just left of the white Keck domes near the photo's center. Subaru is the latest in the class of optical telescopes using a mirror with a diameter greater than 8 meters. Subaru's 8.3-meter primary is the largest single-piece optical telescope mirror yet made , and is so thin that its precise shape can be monitored and adjusted. ... February 1999 . ... Publications with keywords: optical - telescope . ...