A discussion on orbital analysis - Tracking by the Smithsonian Astrophysical Observatory

Abstract

A world-wide network of photographic observing stations was conceived at the Smithsonian Astrophysical Observatory (S.A.O.) more than 10 years ago to track the artificial satellites proposed for the International Geophysical Year (I.G.Y.) (Whipple & Hynek 1958). The United States planned to launch its I.G.Y. satellites from Cape Kennedy into orbits with low inclinations. Therefore the original locations of the astrophysical observing stations were selected to obtain the best practical coverage of these low-inclination orbits. Baker-Nunn cameras (see figure 1, plate 2) and Norrman time standards were installed at the familiar positions shown in figure 2, with the essential cooperation of and participation by the governments and scientific institutions of the host countries. The network operated as planned during the I.G.Y. and subsequently became an important part of the U.S. space program. The initial scientific objectives of the S.A.O. satellite-tracking program have all been realized or have surpassed expectations, as will be clear from later papers in this Discussion. Today, the S.A.O. network and its operation differ significantly from the patterns established during the I.G.Y. Thus a review of the current status is timely. For this review, the changes have been grouped into five topics: (1) New station locations in the network. (2) Instrumentation and modes of operation. (3) Interface with other networks and instruments. (4) Selection of satellites for tracking. (5) New scientific objectives. These topics are discussed individually below.