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: Sight Reduction Formula Question
    From: Fred Hebard
    Date: 2005 Jan 7, 17:02 -0500

    Dear Fried Squash,
    I'd salute you by name, but can't find it in your posts, which I can
    understand as a desire to avoid spam, etc.
    The one thing to watch out for in Turner's book is that he mentions
    that one can determine interstellar angles when the stars are at equal
    altitudes, without accounting for refraction.  This is simply wrong.
    One might want to calculate those angles to measure sextant accuracy.
    Other than that, I found the book very useful.  This error also is
    present in Bruce Bauer's book, The Sextant Handbook, and, I believe, in
    modern editions of Bowditch.
    BTW, Welcome to the list!
    On Jan 7, 2005, at 11:19 AM, Fried Squash wrote:
    > Thanks Fred, you are absolutely correct, Turner does
    > indeed explain that the short one can yield 180 deg
    > ambiguity.  I should have kept reading.
    > --- Fred Hebard  wrote:
    >> I believe Turner gives the reason for the longer
    >> formula and also shows
    >> the shorter one, saying the shorter one can be
    >> inaccurate in some cases.
    >> Fred
    >> On Jan 7, 2005, at 10:24 AM, Fried Squash wrote:
    >>> In _Celestial for the Cruising Navigator_ by Merle
    >>> Turner, the navigational triangle azimuth formula
    >> is
    >>> given as:
    >>> cos Z = (sin d - (sin L * sin H ))/(cos L * cos H)
    >>> but Dutton's Navigation and Piloting gives the
    >> much
    >>> simpler:
    >>> sin Z = ( cos d * sin t ) / cos H
    >>> They both seem to work.  But there must be some
    >> reason
    >>>  that the longer one is better, right? Works in
    >> more
    > __________________________________
    > Do you Yahoo!?
    > Read only the mail you want - Yahoo! Mail SpamGuard.
    > http://promotions.yahoo.com/new_mail

    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