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: V-Correction for Sun? Answer from UKHO...
    From: Gary LaPook
    Date: 2016 Oct 14, 23:43 -0700

    Just like the NA the Air Almanac was designed to provide the appropriate level of precision necessary for the type of navigation, inflght celestial navigation so it eliminates interpolations and provides the data only to a precision of whole minutes of GHA and declination (in the normal practice) thus speeding up computations. Since the accuracy of in fllight observations is in the order of several minutes it would be of no purpose to provide the data to a higher level of precision. It does provide a way to determine GHA sun and Aries to a tenth of a minute for use with astro-trackers which can track stars to a higher level of precision than a can a bubble sextant. 

    Also of interest, at the bottom of each column is tabulated the actual rate of hourly GHA and declination change but no mention of these tabulations is made in the Almanac and these could be used in place of a "v" or a "d" correction but this level of sophistication is not warranted for flight navigation and no interpolation tables are provided to allow utilization of these tabulated values. See attached sample page of AA.

    gl

    --------------------------------------------------------------------------------

    Well that’s a relief.  I really was beginning to wonder if I’d been doing it wrong all those years.  However, I’ve just waded through all 909 pages of the current US Air Almanac and was unable to find one mention of ‘v correction’, so that explains it.  The ten minute spacings must make it unecessary.  Incidentally, it still contains some great star diagrams and duration of twilight diagrams. Unfortunately, it’s not easily available in the UK except on-line, and if it was, it must weigh a ton. DaveP



    File:

      

       
    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