AstroCalc is a Astro / Celestial navigation program and tutorial. If you're looking for a tutorial giving a painless introduction to the ancient art of navigating by the sun, moon or stars, then look no further. If you're an experienced navigator, wanting a program that offers long term precision ephemeris, sight reduction, the utmost simplicity and one that's intuitive to use, then AstroCalc is written with you in mind.

Its mathematical routines have has been developed over 15 years and have been well proven by many circumnavigators and long distance cruising sailors. However, a main feature is its apparent lack of features, or rather, a lack of complex options. AstroCalc will not tax your computer skills which need to be no greater than you've already used to display this pages.

If you are living ashore you may well find it difficult to find a spot with a clear view of the sea horizon that's essential for taking conventional sextant sights. Even if you are fortunate enough to live near to the coast, you may still find that the horizon you see is too narrow, not beneath the objects you intend to observe or or perhaps obscured by off-lying islands. The answer to these difficulties lies in the use of an Artificial Horizon. In its simplest form this could be puddle or bowl of still water. If you are using the Sun, stand so that you can see it reflected in the water and use the sextant to bring the image of the true Sun down to coincide with its reflection. A little dye in the water may improve the reflection. Some commercially produced artificial horizons have transparent shields that form a tent over the surface to shield it from wind. Other fluids that have been used successfully include oil or even mercury.

Recording your results
To record your observations, draw up a short table with columns for data items that you'll be transferring to AstroCalc and for the results you'll be computing.

The license of this software is Free Trial Software, the price is $40.00, you can free download and get a free trial.