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: Sidereal Hour Angle vs. Right Ascension
    From: Henry Halboth
    Date: 2005 Aug 16, 14:08 -0400

    Prior to 1933, determination of stellar or planetary hour angle involved
    the use of siderial time and right ascension. Thereafter, GHA was
    tabulated in the NA until the advent of the current style publication, in
    which SHA is employed for stars.  Each subsequent "modernization" has
    significantly reduced the navigator's work, particularly in the area of
    interpolation. Abstracting the relevant almanac data was at one time a
    greater chore than the rest of the solution.
    The foregoing speaks only to American convention.
    On Mon, 15 Aug 2005 09:41:02 -0400 Robert Eno 
    > I was looking through some old almanacs over the weekend and noted
    > that in the 1940's at least, the almanac provided celestial
    > coordinates in terms of right ascension, in hours and minutes.
    > Can anyone tell me at what point in time navigators moved from using
    > right ascension to sidereal hour angle for reckoning celestial
    > coordinates?  Why was this done?
    > My first guess is that SHA is easier because one does not have to
    > reckon with hours and minutes but instead, uses the more familiar
    > degrees and minutes. Nevertheless, this is the system that I learned
    > so it would naturally appear to be easier.
    > Robert

    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