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: When did the Atumnal Equinox occure this year?
    From: Frank Reed
    Date: 2019 Sep 25, 14:25 -0700

    Steve, have a look at the Sun's SHA on that date. One way to do this is to check the USNO web app that we've been discussing. Start here: https://aa.usno.navy.mil/data/docs/celnavtable.php. Then enter time and location date to end up here. Though this tool does not directly display the Sun's SHA, you can easily calculate it: SHA* = GHA* - GHAaries. This approach based on SHA works well on the equinoxes and the solstices, too. On the equinoxes, since the Sun is moving rapidly in Dec, you can also check to see when the Sun's Dec changes from its hemisphere North/South. The times may not exactly match due to a couple of minor issues, but they will be close.

    Frank Reed

       
    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