Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    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:
    http://www.navigation-spreadsheets.com/lops.html

    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
    described."

    ==================

    Here it is, attached.

    George.

    george-at-hux.me.uk

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



    --~--~---------~--~----~------------~-------~--~----~
    NavList message boards: www.fer3.com/arc
    Or post by email to: NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)