Celestial navigation with a phone camera
If you don't have a sextant to hand, then alternatively you can shoot celestial navigational sights with your phone. Best suited are the moon and the brightest planets, Jupiter and Venus. Less so the sun (too bright) and stars (mostly too dim)
Here we demonstrate a moon sight using our Android app for measuring Angular Distance
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The screenshot below shows the above twilight scene as captured by the app. To measure the rising moon's altitude above the horizon, first pan and zoom (drag and pinch gestures) to center the cursor over the moon. The slider top left controls the cursor diameter. Once aligned, press the 'pin' button bottom right.
Now hit the button top left (⟂) to toggle a horizon line reference. Pan and rotate this reference line to match the horizon of the photo. We don't have an open sea horizon in this example, but the shoreline of the farther island to the right will do fine as a so-called 'horizon short'.
That's it for the altitude measurement. To do the sight reduction calculation and and plot the resulting line of position, hit the sextant icon button to export the measured altitude to Celestial Navigation 360. The latter opens directly in a New Sight wizard for the date/time and altitude it has received.
Don't forget to set Dip consistently with the horizon/short as you step through the wizard
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