Astronomical Almanac for the Year 2013 and Its Companion, The Astronomical Almanac Online

Prepared jointly with Her Majesty's Nautical Almanac Office, United Kingdom Hydrographic Office. Designed in consultation with other  astronomers of many countries. Provides current, accurate astronomical data for use in the making and reduction of observations and for general purposes. The Astronomical Almanac Online extends the printed version by providing data best presented in machine-readable form. Online data are provided for several years. Contains data for astronomy, space sciences, geodesy, surveying, navigation, and other applications.