AstroNav’s accuracy is measured in fractions of an arc-second and contains a comprehensive list of stars visible with binoculars. (Mag 10/ 330,000 stars.) It will produce better results than tables by avoiding their inherent simplifications. (0’.5 is possible)

The difference between a comprehensive list of stars and a selected list is knowing when a sextant observation is ambiguous rather than simply rejecting an inconvenient result. AstroNav will convert a time, sextant altitude and approximate bearing to a plotted Position Line. It will usually identify the /a single body, however there are occasions when a choice exists in which case this will be apparent. (See Sights.) Up to nine sights can be combined while allowing for changes in course/ speed.

AltAz provides Sextant, Observed or True Altitudes together with True and/ or Magnetic bearings. These are always based on the position method chosen. (Fixed, by track or using a voyage plan. It can also be used to list stars around a point in the sky.

The Almanac screen can be used to produce conventional Nautical Almanac pages for any date between 9999 BC to 9999 AD. These can be used as backup or reference.

Celestial data has other applications thus the Twilight screen will calculate the times of Sunrise, Sunset and twilights for a month or voyage. Similarly data for the Sun, Moon and planets can be viewed over a period using the Solar Bodies Screen.

The position(s) used to generate data can be fixed, by course/ speed or using a Voyage plan. The Dead Reckoning (DR) position offers an independent check on a vessel’s position.

Information about Moon Phases and Eclipses is also available between 9999 BC and 9999 AD

The common name of over 500 stars are included together with many alternatives. (Sirius, Dog Star, Al Shira etc.) Over 3,400 stars have Bayer and/ or Flamsteed designations. Henry Draper, Hipparcos, GCVS and Tycho designations are also available. Any of these can be used to find a star.