Essential astronomical information for every kind of sea-going vessel, from cruise liners to fishing boats, this comprehensive almanac contains a set of concise sight reduction tables for the navigator, together with all the necessary information needed for use in determining the position at sea from sextant observations. This book has been jointly prepared by HM Nautical Almanac Office and the Nautical Almanac Office at the United States Naval Observatory, to meet the requirements of the Royal Navy and the US Navy.