The Smithsonian Astrophysical Observatory (SAO) operates a worldwide network of observing stations. These stations obtain experimental data from which precise satellite orbits are computed on a CDC 6400 computer at the Observatory's headquarters in Cambridge, Massachusetts. In contrast to many other tracking systems, real-time data are not essential. It can take as long as a year to obtain the necessary time corrections, apply these, and compute the orbits. The important requirement for the useful scientific applications of the results is the accuracy of the computed orbits. And, of course, the accuracy of these orbits depends upon that of the data obtained from the tracking system.
C. G. Lehr,
L. A. Maestre,
P. H. Anderson,
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