SIGHT REDUCTION TABLES FOR AIR NAVIGATION - Vol. II & Vol. III (2 VOLUMES)

This series of sight reduction tables, comprising three volumes, contains computed altitudes and azimuths representing solutions of the navigational triangle as required in usual navigational practices employing modern line of position methods. The tables are planned for use with The Air Almanac. Auxiliary tables are frequently revised to reflect changing requirements. Since previous printings the auxiliary tables have been reoriented in Volumes II and III and corresponding changes effected in Volume I, causing some changes in entering arguments and tabulation intervals. The list of 57 Selected Stars will appear in each volume. The most frequently used auxiliary tables are duplicated on an insert distributed with each volume. 

Volume I, for selected stars, is arranged for entering with latitude, the hour angle of Aries, and the appropriate star name. This arrangement minimizes the time and effort required in sight reduction. Progressive changes in the coordinates affecting the tabulated data necessitate recomputation at approximately five-year intervals in order to reduce the effects of this source The tables for epoch 1965.0 were the first to include seven selected stars, of cumulative error. chosen with emphasis upon their distribution in azimuth. This objective has resulted in the inclusion of a larger number of lesser magnitude stars than in previous editions. The three stars marked by asterisks provide sets favorably situated in altitude and azimuth for fixing purposes. The successive printings of Volume I for epoch 1970.0 replace the edition for epoch 1965.0. A GHA Table for emergency use has been included. As in the preceding edition, the azimuth is measured from true north, and refraction is not included.

Volume II, for latitudes 0°-39°, and Volume III, for latitudes 40°-89°, provide complete data for the reduction of sights of sun, moon, planets, and stars within the declination range of these bodies, extending from the zenith to the horizon and below. In contrast with Volume I, azimuth angle is tabulated instead of azimuth. The data, and hence the tables, are considered permanent in scope and character. The arrangement of both volumes, with entering arguments of latitude, declination, and hour angle, is similar to that of the volumes of H.O. Pub. No. 214, Tables of Computed Altitude and Azimuth. The latter tables comprise one of the most comprehensive series available for the accurate reduction of marine observations. Table 4, the GHA and Declination of the Sun, is included in both volumes for use should an almanac be inaccessible.

The preparation and publication of these tables represent the collaborative efforts and joint accomplishments of the U.S. Naval Oceanographic Office, the U.S. Naval Observatory, and H.M. Nautical Almanac Office.