Example Screen Shot


AstralNav - A program for Celestial Navigation.

The AstralNav software is designed to calculate the geographical position of a user, from celestial observations, (like those from a sextant). The observations are used to automatically fix the users location by "Line of Positions" (LOP).  The LOP traces can be optionally displayed on actual map images (from OpenStreetMaps), that will (optionally) automatically download and save to a user selected directory.
The software also includes a graphical map of the night sky, that enables the user to locate the standard stars utilised in celestial navigation.  The software thus also provides various astronomical data, such as the data obtainable from the Nautical Almanac.


The "Lines of Position" module will calculate and plot the fix lines, from user entered data from a sight object (star, sun, moon, or planet) data, to determine the users Latitude and Longitude.
The features of the module are:
  •     Standard altitude corrections are performed including: Index Error, Height of the Eye, Parallax, Semi-Diameter, and Refraction.
  •     Calculates and draws of Lines Of Position (LOP), and calculates the Latitude and Longitude.
  •     Loading and saving of data.

The "Star and Planet" module provides astronomical data, similar to that obtained from a Nautical Almanac.
The features of the module are:
  •     Astronomical data for the Sun, Moon, 4 planets and 57 standard Navigation Stars (of the Nautical Almanac), and some other major stars.
  •     Provides numerous data: Such as GHA, SHA, DEC, Semi-Diameter, Horizontal Parallax, and Equation of Time.
  •     Calculations for any day/year, (accuracy based on the calculations used in the module).

The "Star Map" module provides a polar and linear plot of the sky at a given time and geographical position.
The features of the module are:
  •     Plots (if visible) positions of the Sun, Moon, 4 planets and 56 stars.
  •     A Polar plot (overhead) plot is available.
  •     A linear plot (against GHA or SHA) of the astronomical data is available.
  •     The plotted objects name, altitude and azimuth is provided in a list.
  •     Objects can be identified by mouse click.
  •     Time can be incremented and decremented by mouse wheel.


This is fully functional FREE software.

The author wrote this software for their own purpose, and has been utilising (and updating) this software since around 2010.
This software performs functions similar to other Astral Navigation software (including other free software).
However, after getting interested in Astral Navigation, I was disappointed by the "free" Astral Navigation software available. Hence I started to code my own software, initially just to perform the complex sight reduction calculations, for plotting (with the user requiring to input data from the Nautical Almanac).
After researching astronomical calculations and finding the free Astronomy C/C++ source code by Mark Huss (, the software was expanded to automatically calculate the data (otherwise obtained from the Nautical Almanac).


No liability whatsoever for the program operation, use of the data, accuracy of the data, loss of information, or anything else is accepted by the author of this program.


PKZiped of the program and help files:

    (~1.0 MB PKzip file)

Unzip the above file (to a user accessible directory), and run the new unziped file "AstralNav.exe".