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    Re: Latitude by law of cosines
    From: Chris Caswell
    Date: 2018 Jan 23, 12:07 -0800

    Frank Reed, you wrote:

    Chris Caswell, you wrote:
    "Are you saying John Karl's equations are wrong, or inaccurate?"

    Chris, I thought I was pretty clear on all of this, but let me try to re-phrase:
    First things first: you don't need this! No one calculates latitude this way, except in quite peculiar circumstances. It is never the case that we know the exact hour angle (or equivalently the exact GMT and longitude) and do not know our latitude. This is just one of those little "idiosyncracies" in John Karl's book. There's plenty of good material in there, of course, but also quite a few oddball bits like this that are not properly explained. If you never saw this calculational trick in your whole life as a navigator, you would not be diminished in any way.

    Let me ask you, Chris, do you have any questions about what I have just written in this paragraph? Do you understand what I am saying here? Please feel free to ask for clarification.

    Yes, Frank, got it. I also get noon sights, and have done just a few.

    Frank Reed wrote:

    You talked about wanting to solve a middle-of-nowhere scenario, where a navigator is "dropped" somewhere in the world with no clue about location. I want to assure you, again, that the equations you previously referenced in John Karl's book are not the answer... and they're not an answer. I am not being disingenuous when I tell you that there's no real use for that particular set of equations in a scenario like this (or, indeed, any practical scenario).

    Do you understand what I am saying here? Do you have any specific questions about what I have said here?

    Got that as well.

    Frank Reed wrote:

    But just so you know, there is an algorithm in Karl's book which some people cite as a tool for solving exactly this sort of middle-of-nowhere mystery. It's at the end of chapter 7 on "special sights", his formulas 7.5a-f. There are different printings of this book, and the pagination of yours doesn't match mine (as I have alread discovered) so I won't give a page number. I hope that description is enough to find the formulas in question, and you can explore those as you like. They are straight-forward, though a bit tedious.

    I have found the reference and will look into it.  Thank you for all your time and help.

    Chris in VT

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