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
    A Nautical Almanac question
    From: Stan K
    Date: 2016 Nov 23, 18:52 -0500
    Is the d value listed at the bottom of the sun and planets columns of the daily pages of the Nautical Almanac the average (or mean) hourly change in the sun's declination for the three days listed (as stated in the Nautical Almanac and other references) or the amount the declination changes between 1200 and 1300 on the middle day of the three shown (as stated in Bowditch)?

    I did one page of the sun values in the 2017 Almanac and found that, after rounding to tenths of an arc-minute, the average was 1.0', the change between 1200 and 1300 on the middle day was 1.0', and the value at the bottom of the declination column was 1.0'.  I suspect that I would find the same thing on other pages, but I'm curious if anyone knows for sure.  My suspicion is that Bowditch is correct, and the references using "average" or "mean" are just simplifying the explanation.


    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