Explanatory Supplement To The Astronomical Almanac Pdf Download =link= Link

You can borrow or stream a complete 1992 edition (reprinted 2006) for free.

| Edition | Year | Editors / Contributors | Notes | |---------|------|------------------------|-------| | 1st | 1961 | U.S. Nautical Almanac Office (USNO) & H.M. Nautical Almanac Office (HMNAO) | Long out of print; concepts partially superseded. | | 2nd | 1992 | P. Kenneth Seidelmann (ed.) | Major update, now historical but still widely referenced. | | 3rd | 2012 | Sean Urban & P. Kenneth Seidelmann (eds.) | Most current; includes modern IAU resolutions, ICRS, relativistic models. | You can borrow or stream a complete 1992