2018 This edition was upgraded with a QR code linking to an application with more resources including videos & links to official websites including Wikipedia, NOAA, NGA, and IHO.
This six-volume series of Sight Reduction Tables for Marine Navigation is designed to facilitate the practice of celestial navigation at sea by the Marcq Saint Hilaire or intercept method.
The tabular data are the solutions of the navigational triangle of which two sides and the included angle are known and it is necessary to find the values of the third side and adjacent angle.
The tables, intended for use with The Nautical Almanac, are designed for precise interpolation of altitude for declination by means of interpolation tables which facilitate linear interpolation and provide additionally for the effect of second differences when required.
The concept, design, development, and preparation of these tables are the results of the collaborative efforts and joint accomplishments of the National Imagery and Mapping Agency, the U.S. Naval Observatory, and Her Majesty's Nautical Almanac Office, Royal Greenwich Observatory. The tabular material in identical format has been published in the United Kingdom by the Hydrographic Department, Ministry of Defence (Navy), as N.P. 401.
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY