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: Peter Hakel
    Date: 2019 Sep 27, 05:52 -0700

    Frank, you asked about the values of Sun’s SHA around the autumnal equinox this and the next year.

    The attached spreadsheet displays the right ascension of the Sun (“Alpha” in cell A61), which works equally well as the SHA. For September 23, 2019 we have

    UT = 07:49:58
    Alpha = 179.9999899 degrees

    UT = 07:49:59
    Alpha = 180.0000003 degrees

    which are the two times bracketing the change in declination sign reported in my previous post.
    Delta T is computed to be 71.4 seconds (cell B16).


    For September 22, 2020 I get
    UT = 13:30:31
    Alpha = 179.9999899 degrees

    UT = 13:30:32
    Alpha = 180.0000003 degrees
    Delta T is 72.0 seconds. The declination sign change from N to S is bracketed by these two time instants as well.


    Peter Hakel

    File:
    f1-sun.xls
       
    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