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    Re: two-body computed fix. was: assumed positions
    From: Peter Hakel
    Date: 2009 Sep 25, 19:16 -0700
    Thank you, George, for providing historical information and the Gery paper.

    I reproduced the results of the special case in Appendix B of this paper.  My procedure is essentially identical to the Van Allen method:

    I was also able to confirm the main solution of the Spica/Venus example from page 19.  However, my second ("spurious") solution has a different longitude.  I obtain:

    S     53 deg 28.4'   (same as in the paper)
    W  108 deg 51.5'   (as opposed to W 101 deg 36.7' from the paper)

    I verified that all my fixes yield 0.0 intercept distances when used as APs.  This is also the case for Gery's (spurious) fix when using Spica's GP.  With Venus, however, I calculate intercept of 256.9 nm Away when using the longitude from the paper.

    The published longitude could be a misprint or there is a very subtle flaw in the method.

    Peter Hakel

    From: "george@hux.me.uk" <george@hux.me.uk>
    To: NavList@fer3.com
    Sent: Friday, September 25, 2009 12:29:30 PM
    Subject: [NavList 9924] two-body computed fix. was: assumed positions

    In [9921], Lu Abel asked-

    "Is Gery's paper (or a similar one on direct calculation of L/Lo from a
    pair of observations) available on-line?

    One would guess that with two observations (and, of course, all the time
    and NA data) one could calculate L/Lo directly, but I've never seen it


    Here it is, attached.



    Linked File: http://www.fer3.com/arc/imgx/v44n1-2.pdf

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