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: Lunar Distance Puzzle
    From: Dave Walden
    Date: 2011 Aug 19, 18:36 -0700

    It REALLY does work!

    Here's a case generated with Frank's online calculator. (No NOVAS, no JPL) I have no knowledge of what refraction calculation he uses. I pick a time and place and iterate on LD until I get zero error for each of the three stars. I do near and far, then average since I'm dealing with centers at the moment. I use his almanac data. I round the LD's to the nearest 10th of a minute. Seems like a pretty fair test. I get within 20 seconds and 10 nm starting from an hour off in time and 70 miles off in AP. Not bad for the 10th of a minute LD and linear interpolation between hours.

    Nautical Almanac Data for August 16, 2011
    Date and Times are GMT.

    16:00 17:00
    Moon's HP 54.39 54.38
    GHA Aries 204° 42.1' 219° 44.6'
    Greenwich Hour Angle
    and Declination
    The Moon 210° 23' 21"  224° 58' 11" 
    N 3° 1' 42" N 3° 13' 24"
    Fomalhaut 220° 7' 9"  235° 9' 37" LD 33d 23.6m
    S 29° 33' 21" S 29° 33' 21"
    Hamal 172° 44' 14"  187° 46' 42"  LD 41d 58.2m
    N 23° 31' 5" N 23° 31' 5"
    Markab 218° 21' 27"  233° 23' 55"  LD 14d 59.0m
    N 15° 16' 16" N 15° 16' 16"

    (used 50d F, 29.83 in Hg, 0 IC, 0 ht of eye, include both corrections)

    with LD's the the second (which Frank's calc can do):

    time err -4.6s
    lat err .1 nm
    long err 3.1 nm

    for those who are doing it:

    33d 23m 45s

    41d 58m 14s

    14d 59m 1s

    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    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