Marine Glossary

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Azimuth Angle

The relative bearing (between 0° and 180°) of a celestial body viewed from the assumed position at the time of the sight. It is found in the sight reduction tables (Workform, Box 5); it is measured relative to due north in north latitudes and relative to due south in south latitudes. Abbreviation capital Z. See Navigational Triangle. Z is to be distinguished from Zn, the azimuth.

Added later from our class notes for more clarification:

Z and Zn are just ways to specific a direction. Zn is identical to what is usually called Azimuth, i.e. a true bearing 0 to 360 relative to true north at 000.

Azimuth angle is a relative bearing, relative to the elevated pole–that is, relative to North in the NH and South in the SH. It is given as 0 to 180, without a sign, as this is then determined by the LHA in cel nav. Note that Z by itself is ambiguous, it could be to the left or right of the reference direction.

This is a cel nav concept, invented purely to simplify the presentation of mathematical solutions to the navigation triangle. I do not know of any use of this concept at all away from sight reduction tables.

It has asymmetric rules for converting Z to Zn in NH and SH, because both use the elevated pole for reference (opposite directions), but we use due north for true bearings in both NH and SH.

Abbreviation: Z