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: Moon sight?
    From: Bill B
    Date: 2014 Oct 05, 15:50 -0400

    On 10/5/2014 12:31 AM, Sean C wrote:
    > Would you please explain to me the formula you use for Refraction and
    > where you got the figures? The 7.32 and 4.32.
    
    Sorry about the my answer. Off base as I commingled two of my projects
    in my memory.
    
    The  7.32 and 4.32 are very similar in value to those used in Bennett's
    simple formula on page 106 of Meeus's "Astronomical Algorithms," but the
    formula's differ.
    
    Bennett's formula is:
    
    R (in arc minutes) = 1/tan (ho + 7.31/ho + 4.4)
    
    ho = apparent altitude = Ha
    
    Bennetts's formula from Wikipedia
    http://en.wikipedia.org/wiki/Atmospheric_refraction
    
    R=cot(ha + 7.31/ha+4.4)
    
    As Bennett's is referred to as a "simple empirical formula," and Bennett
    gives two methods of refining the results, I would surmise the NA
    version is more rigorous.
    
    Bottom line, this does not answer you math/physics question of how the
    constants and formula's were derived. Some of the list Guru's may help
    out there.
    

       
    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