– Contains scanned older editions (e.g., 1961, 1974, 1992).
The physical hardcover of the 2012 edition (ISBN 978-1891389856) typically retails for $80–$120. Used copies of the 1992 edition can still run $50+. For many students, independent researchers, or amateur observatory operators, this cost is prohibitive. Furthermore, the book is heavy and not easily searchable. – Contains scanned older editions (e
: The first edition appeared in 1961. By 1992, the International Astronomical Union (IAU) had introduced such massive changes to astronomical theory that the supplement had to be entirely rewritten to account for new reference frames and planetary models. – Contains scanned older editions (e.g.
If you are unable to access the USNO website or prefer alternative sources, you can try the following: or amateur observatory operators