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    Re: No DR position. How can you get an accurate celestial fix?
    From: David Pike
    Date: 2020 Jan 24, 11:41 -0800

    Bill Lionheart you wrote: What I have in mind is to prove a result that says "if you are
    within some specific distance of the correct position th iteration
    converges", and I think it is pretty clear it can fail if you are far
    enough away. As I said it is pretty much Newton's method on a sphere,
    and there are plenty of general results about convergence of that.

    Best of luck.  Do you intend to include other conditions such as the minimum acceptable cut, 30 degrees say?  This would depend upon: time between observations; difference between DR and true position (because different positions will affect calculated azimuths.  Above 23.5N the more north the error, the more the cut will reduce. E.g. look at it for LOP1 0800, LOP2 12.00); and your westerly component of MOO.  Finding the longitude of an aeroplane flying with a westerly component of 15 degrees per hour might present a problem however close the DR to the true position.  DaveP

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