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
    Name or NavList Code:
    Email:
       
    Reply
    Re: Determination of the GHA of Aries
    From: David C
    Date: 2020 Sep 9, 21:49 -0700

    David I wrote

    The relationship between GHA Aries and UT has a fixed definition that increases.  The rate is almost entirely linear and treated as an increase in GHA Aries of 2.46' per hour UT by the Nautical Almanac.  Historically this difference has been referred to as the "right ascension of the mean sun" and some modern texts still refer to it by the letter R.

    Prior to the introduction of the GHA almanac in the 1940s the values R and E were tabulated, where

    R = Right Ascension mean sun +- 12 hours

    E = 12 hours - EOT

    R & E were introduced to simplify calculations.

    OTTOMH I cannot remember when R and E were introduced.

    The attached copies are from the 1929 almanac and the 1930 edition of Nicholls Concise Guide.

    File:


    File:


       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID 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