Celestial Navigation Math

With an electronic calculator and a few simple formulae, you can replace several volumes of tables with just a few simple equations.

Sight Reduction

Given Assumed Position, AP (lat, lon) and Geographic Position of a body, GP (declination, gha), the computed altitude (Hc) is found by:

Here is a simple Javascript calculator for you to play with.

Latitude: Hc: 0
Declination: Z: 0
LHA:
lha = gha - lon sin(H) = cos(lat)*cos(dec)*cos(lha) + sin(lat)*sin(dec)

and the azimuth (Z) is found by:

sin(dec) - sin(H) * sin(lat) cos(Z) = ---------------------------- cos(H) * cos(lat) if( lha <= 180 ) Z = 360 - Z