provides official information about the supplement, including historical context and how to order current editions. Scribd & SlideShare
There is no authorized, free, public-domain version of the third edition of the Explanatory Supplement available from the USNO or HMNAO. It is a copyrighted work that is actively sold by its publisher. Any website claiming to offer a "free download" should be treated with caution. The safest, most reliable, and ethical method to obtain a complete, high-quality digital copy is to purchase it from the official publisher or a legitimate academic retailer. Any website claiming to offer a "free download"
Predicting exactly when one celestial body will pass in front of another. Star Catalogs: Star Catalogs: The book is prepared jointly by
The book is prepared jointly by the Nautical Almanac Office of the United States Naval Observatory (USNO) and His Majesty's Nautical Almanac Office (HMNAO) in the United Kingdom. First published in 1961 to explain the unified almanacs of the US and UK, it has undergone major revisions to keep pace with modern computing and observational accuracy. provides official information about the supplement