Astronomy has taken a significant step forward with the success of NASA's Orbiting Astronomical Observatory designated OAO-A2 (Figure 1). This 4400 pound satellite, the heaviest and most com-plex unmanned observatory developed by the United States was launched on December 7, 1968, from Cape Kennedy. It has now entered its fourth year of operation which represents over 15,000 orbits of which 90 percent have been available for experimentation . During this period of time astronomers have made over 12,000 observations of stars, gal axies, planets, and nebulae. Over one million com-mands have been executed.

Date Published: 1 September 1972
PDF: 14 pages
Proc. SPIE 0028, Instrumentation in Astronomy I, (1 September 1972); doi: 10.1117/12.953522

Published in SPIE Proceedings Vol. 0028:
Instrumentation in Astronomy I
Lewis Larmore; Robert W. Poindexter, Editor(s)