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: equinox
    From: Jay Borseth
    Date: 2004 Mar 21, 16:26 -0800

    I am not an astronomer (IANAA), but I would guess the discrepancy lies in
    the assumed values of deltaT, the difference between Dynamical Time and
    Universal Time.  For a taste of the topic, see:
    
    http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=DWELLS.9
    5Mar19183528%40fits.cv.nrao.edu&rnum=8&prev=/groups%3Fq%3Dusno%2Bdeltat%26hl
    %3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26selm%3DDWELLS.95Mar19183528%2540fi
    ts.cv.nrao.edu%26rnum%3D8
    
    I recently changed the values of deltaT used by Pocket Stars
    (http://www.nomadelectronics.com) to more closely match USNO values:
    
    // julian                         deltaT
    2451544.5000000, /*2000.0000,*/   63.83,
    2453371.5000000, /*2005.0000,*/   66.00,
    2455197.5000000, /*2010.0000,*/   70.00,
    
    Using these values for deltaT, Novas, and DE405, the equinox as calculated
    by Pocket Stars was at 6:48:53.
    
    - Jay
    
    
    -----Original Message-----
    From: Navigation Mailing List [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]
    On Behalf Of Fred Hebard
    Sent: Sunday, March 21, 2004 4:05 PM
    To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    Subject: Re: equinox
    
    Here are the Sun's declination as reported in the Nautical Almanac
    versus time.  Looks pretty linear to me.  The discrepancy may lie
    elsewhere, such as the system of coordinates.
    
    When I said the time was exactly 6:48:00, I meant the calculation
    indicated 6:48:00, not 6:48:01 or 6:47:59.
    
    As both you and I said, it would be nice if an experienced astronomer
    would chime in here.
    
    Fred
    
    
    

       
    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