PLEASE NOTE: this news item was released in October 2002. Check the relevant publications pages for the latest information.
|Rapid Sight Reduction Tables for Navigation AP3270/NP303|
|Volume 1:||Epoch 2005.0 selected Stars||ISBN 011 887555-8||Price £25.00|
|Volume 2:||Latitudes 0°-40° and
|ISBN 011 887556-6||Price £25.00|
|Volume 3:||Latitudes 39°-89° and
|ISBN 011 887557-4||Price £25.00|
|Publisher:||The Stationery Office|
Rapid Sight Reduction Tables for Navigation, in three volumes, also known as AP3270 and NP303, provides essential information for marine navigation. The specially-designed, comprehensive tables of altitude and azimuth, with explanation and detailed worked examples, enable rapid reduction of astronomical sights using traditional techniques. This updated and re-titled edition maintains the format of the main tabulations of Sight Reduction Tables for Air Navigation, however the change of emphasis of the explanation, examples and auxiliary tables reflect the popularity of this publication with navigators at sea.
HM Nautical Almanac Office and the Nautical Almanac Office of the US Naval Observatory designed the tabular pages which are used worldwide; by the US Navy, the Royal Navy, amateur and professional navigators alike. Positions derived from these volumes compare favourably with other astro-navigation publications. The explanation and clearly worked examples with position line plots give an easy method for all navigators to find their position at sea.
Volume 1 contains tables of altitude and azimuth of seven selected stars for the complete range of latitudes and hour angle of Aries. The arrangement provides, for any position and time, the best seven stars to use, their positions for presetting the sextant and their subsequent reduction. The volume, valid for 2001-2010, may be used without reference to an almanac, as it also contains tables for GHA Aries, dip and refraction. Other auxiliary tables include the conversion of arc to time, and corrections due to the movement of the vessel. There are star charts to aid identification and a sight reduction form to record the results.
Volumes 2 and 3 contain tables of altitude and azimuth for the complete range of hour angles valid for latitudes 0° to 40° north and south and 0° to 29° declination north and south (Volume 2) and latitudes 39° to 89° north and south and 0° to 29° declination north and south (Volume 3). The arrangement provides data for any time, for all objects within 29° of the celestial equator and for all locations for presetting the sextant and the subsequent reduction of the sights. Volumes 2 and 3, valid for any date, are designed for use with an almanac and are designed for use with an almanac, such as The Nautical Almanac. However, a table, valid for 2001-2036 (to better than 2') together with the altitude corrections needed for reducing solar observations is included. Other auxiliary tables include dip, refraction for stars and planets, the conversion of arc to time and corrections due to the movement of the vessel. There are star charts to aid identification and a sight reduction form to record the results.
The sight reduction forms that are included with these publications are available here as downloadable pdf files (Adobe Portable Document Format files). The forms for Volume 2 and Volume 3 are identical, while that for Volume 1 is designed to be used with the selected stars published in Volume 1.