AstroNav is an electronic Nautical Almanac that includes a comprehensive catalogue of stars.
By identifying any star from an altitude and azimuth it dramatically increases a sextant’s potential. Every visible body is a potential position line.
The speed with which sights can be plotted means that the quality of the horizon, can be determined by the result. Reasonable sights can be taken at night but few people will take their time to do so using manual calculation because the results are so variable.
The level of detail can be quickly and easily changed. It is a tool that can be used as a simple sight calculator or as a definative astronomical reference.