About the book

The basic problems handled by nautical astronomy are: determi­ning positions at sea from observations of astronomical bodies and determining true directions to obtain compass corrections.

Astronomical determinations at sea are widely employed both in routine sailing in the open sea and, especially, in areas poorly equipped with radio facilities. At the present time, compass correcti­ons in the open sea can still be made only by methods of nautical astronomy.

The methods of nautical astronomy are in certain respects inferior to radio techniques, but the former have a number of advantages, which include complete independence, secrecy of determinations, relatively high accuracy with simple and cheap apparatus, which has the added advantage of not requiring sources of electricity. At the same time, astronomical methods have a number of definite drawbacks: they are hampered by bad visibility and time-consuming computations, which sometimes restrict their application.

The course of nautical astronomy includes the following basic divisions:

(1) the principles of spherical astronomy, which studies the coor­dinates of celestial bodies and their variations and timekeeping;

(2) instruments of nautical astronomy, which include the sextant,

the chronometer, the celestial globe and diameter;

(3) methods of determining compass corrections;

(4) methods of determining the position of a ship at sea or its

coordinates.