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: Advancing position circles: Huxtable vs. Zevering
    From: George Huxtable
    Date: 2006 Sep 22, 05:46 -0500

    I have to report a boob I made in a recent message, when I set a
    problem for NavList members. Geoffrey Kolbe has been struggling with
    it, and has communicated backstage to tell me about it. Perhaps others
    have been strugging in the same way.

    What I did was to miswrite what should have been GHA of a star, as
    SHA. I had mis-transcribed an exanple I had set to readers of the
    Journal of Navigation. Luckily, in that Journal, I had got it right.

    So here it is; right, I hope, this time.
    |
    | It strikes me that perhaps NavList members might like to tackle the
    | simple test-problem that I set, as follows-
    |
    | 1. An observer, at position P1, measures the altitude of a star S1,
    at
    | (Dec1 = 0, GHA1 = 0), to be 30 degrees.
    |
    | 2. Then he travels due North by 60 nautical miles (= 1 degree), to
    P2.
    |
    | 3.. From there, he observes another star S2 (then at Dec2 = N 1
    | degree, GHA2 = W 45 degrees) to be at an altitude of 45 degrees.
    Where
    | on Earth is he then?
    |
    | and concluded-
    |
    | "I challenge Zevering to apply his procedure to the problem as set
    out
    | above, to provide us with initial and final positions for the
    | observer, the initial altitude of star S1, and the final altitude of
    | star S2."

    Geoffrey also queries why I should be asking for the star altitudes,
    when they were a precondition of the problem. That was simply to
    ensure that after the positions  P1 and P2 are deduced, a back-check
    is made to ensure that the result is correct. The erroneous method,
    that had been proposed and I was countering, would fail such a check.

    Sorry about all that. I do seem to be getting error-prone in my old
    age.

    George.

    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.




    --~--~---------~--~----~------------~-------~--~----~
    To post to this group, send email to NavList@fer3.com
    To unsubscribe, send email to 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)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site