[don1reed]

Hi UG.

I think what a lot of folks don't see from the git-go, is that one cel nav observation only provides us a Line Of Position (LOP). After we take several cel nav sights spaced apart by several hours during daylight (sun), then we can advance our first LOP to our most recent sun sight based on the distance we travelled since taking the first sight, (called a running-fix), and usually (if we did everything right), the two LOPs intersect. Its at the point of intersection where we then construct (pencil & straightedge & protractor) our true heading and position on the chart.

Usually, sailors do this in the morning, noon, & evening.

At night, they use stars, planets, moon. Whats different at night (evening/morning twilight accually) of course is that its possible to get three or more heavenly bodies during one sighting. (spaced about 120° apart) This provides a FIX. No need to do a running-fix as with the sun alone.

Sometimes during daylight its possible to observe sun and moon fix, this also eliminates having to do a running-fix.

...and thats the short 'n long of it.

...oh...one more thing...just like shooting torps at a target...the closer that two LOPs are to 90° intersection, the more accurate the fix.