Multiple sights allowing for changes in track. 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.

The outlines of the constellations is the best available including ones like Sextans which rarely look like a sextant. Bayer/ Flamsteed designations are provided for over 3,400 stars together with the names of over 500 stars. Henry Draper, Hipparchos Tycho and GCVS designations are also available. The Voyage Plan is a sophisticated tool on its own. Tracks can be calculated from positions or tracks can be used to generate positions. ETAs can be calculated from speeds or speeds calculated from ETAs.

The date and time is initially taken from the computer's clock but can be changed as required or updated to the current time using "Reset Time" at the top of some screens. Other settings are changed using the Options screen.

If the mouse pointer hovers over an input box, a popup will show the expected format. "#" is used to indicate a numeral thus "###.#" might be 123.4 or 12.3. The level of help provided by popups can be controlled from the Options/ Misc tab.

The time zone can be entered manually or driven by the computer's settings. In the later case, the time zone will be automatically adjusted for Summer Time.

The "Position" tab offers a choice of the methods used to estimate positions for most data. A voyage plan allows for alterations of course and/ or speed. A single track is limited to one year and the vessel will stop at the North or South Pole. Position errors are flagged by a symbol by the date in each screen if appropriate.

A popup with the reason for the error will trigger if the mouse is allowed to hover over the symbol. Popups for this and disabled features are not disabled at the lowest level of help popups.

Requirements:
* Display size 800x640

The license of this software is Free Trial Software, the price is $32.00, you can free download and get a free trial.