Getting Started (iOS)
Celestial navigation exploits the principle that every measurement taken with a sextant converts to a line of position on a chart, the intersections of two or more such lines providing a position fix.
1 - Set Assumed Position
2 - Sight Preparation
Switch to the Shoot view, it shows the computed horizon at the given Assumed Position, and should therefore correspond fairly well to the real world horizon you see about you.
3 - Enter a Sight
4 - Lines of Position
Hovering the cursor over an LoP activates a green inspection box, showing sighted body and shoot time along with a discard option.
6 - Advanced
An extension flap on the inspection box reveals the LoP's intercept parameters, useful for accurate transfer to a physical chart, running fixes etc. They comprise the azimuthal bearing Zn of the sighted body with respect to AP, and the perpendicular distance from AP to the LoP, given in nautical miles, NM.
Click on the detail icon next to the intercept parameters to see the sight reduction housekeeping from which they derive.