Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Puzzled by Kaplan's 'Motion of the Observer in Celestial Navigation'
    From: Peter Hakel
    Date: 2011 Jun 20, 21:47 -0700

    This trick does not employ the intercept method of St. Hilaire, so the Hc and Zn don't get to be used.  Instead, the author defers to Reference [5] for the direct calculation of the "two-body fix" by two intersecting circular LOPs.  The "running fix" is achieved here by shifting the center of one of these LOPs (Eq. 3), which effectively accounts for the motion of the vessel.  The solution is then found according to Reference [5]; or, e.g. see Section 1 in:


    and references therein (James A. Van Allen, John Karl).

    Peter Hakel

    From: Richard <cnav@barsoom.plus.com>
    To: NavList@fer3.com
    Sent: Sunday, June 19, 2011 7:36 PM
    Subject: [NavList] Puzzled by Kaplan's 'Motion of the Observer in Celestial Navigation'

    I wonder if anyone here could help me. I have just read George Kaplan's paper 'The Motion of the Observer in Celestial Navigation', and have found something that puzzles me.
    In the section 'Adjustment of Celestial Coordinates', he presents an equation to obtain a new GP that, when fed into a sight reduction process for the new AP, will produce the original altitude and azimuth.
    I don't understand the purpose of this - why run a new sight reduction that is (by design) just going to produce the same Hc and Zn ?
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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