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: Ageton HO 211 accuracy 1944 article
    From: Gary LaPook
    Date: 2015 Oct 29, 21:24 -0700

    See:

    http://fer3.com/arc/m2.aspx/HO-211-Ageton-accuracy-test-Hirose-jun-2009-g8786

    http://fer3.com/arc/m2.aspx/Ageton-method-HO-211-Hirose-sep-2014-g28733

    http://fer3.com/arc/m2.aspx/Ho-211-Griffiths-jan-2002-w5068

    http://fer3.com/arc/m2.aspx/HO-211-Bayless-Hirose-sep-1999-w2340

    I have a 1937 edition of HO211 and also Agetons 1942 manual in which he adds an additional table. I am attaching an example of that table I and examples from HO208 and Weems Lline of position book. If you compare the tables you will see that Agetons "B" column is the same as the "A" column in both HO208 and in Weems; his "K" is the reciprical of the "b" in HO208 and his "z" is the same as the "z" in HO208.

    gl

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

    Ageton HO 211 accuracy 1944 article
    From: Paul Hirose
    Date: 2015 Oct 29, 13:16 -0700

    I have the Ageton sight reduction table in three different books but
    don't own a bona fide HO 211. Due to recent discussion I thought maybe
    it's time to buy one. While searching the Web I came across a 1944
    article at the ADS site on HO 211 accuracy by Samuel Herrick. He notes
    Ageton's claim of .5 minute accuracy without interpolation and his
    caution about hour angles near 90 degrees. So is it safe to infer his
    accuracy claim is valid whenever the caution is not applicable?
    
    No, says Herrick. In fact, the maximum error can reach about 6 minutes
    without interpolation. A major source of error is the step where you
    look up function A of side R and take out B of R. (R is the side that is
    perpendicular to the meridian and common to both triangles.)
    
    "The interpolation of B(R) from A(R) will alone reduce the maximum error
    to about two miles for K = 90°, 0.8 mile for K = 80°, and thus bring the
    error within practical limits for most navigation problems."
    
    "In fine, the maximum error of 30 miles that may be found in the use of
    Ageton's table without interpolation sets a dangerous trap for the
    unwary navigator, especially if he be an airman making a sun-line
    approach at sea. But forewarned, he will find a way to his taste for
    avoiding it."
    
    Samuel Herrick, THE ACCURACY OF AGETON'S METHOD IN CELESTIAL NAVIGATION,
    Publications of the Astronomical Society of the Pacific, Vol. 56, No.
    331, p.149 (August 1944).
    
    http://adsabs.harvard.edu/abs/1944PASP...56..149H


    File:



    File:



    File:



    File:



       
    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