The Sight Reduction Tables for Air Navigation are published in three separate Volumes.
Volume I, used by both the marine and air navigator, contains altitude (to the nearest minutes) and true azimuth values of seven selected stars for the complete ranges of latitude and hour angle of Aries. These seven stars represent the best selection for observation at any given position and time, and provide the data for presetting instruments before observation and for sight reduction afterwards. Volume I (AP 3270) is prepared by the Nautical Almanac Office of the U.S. Naval Observatory in collaboration with Her Majesty's Nautical Almanac Office of the United Kingdom Hydrographic Office (UKHO). The UKHO maintains the copyright on the material it produces.
Volumes II and III cover latitudes 0°-40° and 39°-89° respectively and are primarily used by the air navigator in conjunction with observations of celestial bodies to calculate the geographic position of the observer.
The U.S. Naval Observatory provides a Web application that generates Celestial Navigation Data for a given date/time and assumed position.