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
    Re: Moonrise-over-Connecticut
    From: Paul Hirose
    Date: 2021 Nov 6, 14:28 -0700

    On 2021-11-05 14:30, Peter Blaskett wrote:
    >           Celestial Navigation Data for 2021 Nov  6 at 11 43 35 UT (GMT)
    >                                Delta T =  87.7 seconds
    >                   For Assumed Location:  Longitude       0 00.0
    >                                          Latitude        0 00.0
    At that time and place, with the ICE delta T, the Lunar 4.4 program gives:
    Moon geocentric apparent place
    244°53.26' -21°54.44' equinox RA, dec
    135°43.80' +58°35.81' geocentric az, el
    However, the correct delta T is 32.184 (a fixed value) + 37 (until the
    next leap second) - -0.107 (UT1-UTC from IERS Bulletin A). The sum is
    69.29 s. With the correct delta T:
    244°53.06' -21°54.39' equinox RA, dec
    135°43.97' +58°35.99' geocentric az, el
    ICE altitude error is almost 0.2'. Since the ICE delta T is 18.41 s too
    large, the position of the Moon in its orbit is correct if we move UT1
    back that much. But now Earth rotation has not carried the observer far
    enough east. The solution is to convert the time correction to arc and
    move the observer east. Result with the wrong delta T but corrected UT1
    and observer longitude is practically perfect:
    244°53.06' -21°54.39' equinox RA, dec
    135°43.95' +58°35.98' geocentric az, el
    Paul Hirose

    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