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: David Thomson and his lunar tables
    From: Antoine Couëtte
    Date: 2010 Mar 17, 14:58 -0700

    Interesting Lunar indeed ...

    With the following reasonable assumptions that :

    - the indicated sextant values are corrected for Instrument error, and
    - the observer's height of eye is close to 14 feet, and
    - both Lunar distance and Moon + Sun Altitudes took place at the same instant, and
    - delta T = 12.5 s, then with the following :

    Sun-Moon Distance = 71°56', Sun Height LL = 55°36' , and Moon UL = 38°35',

    and with to-day computing tools, we get an observation date of Sep 15, 1809 (and not Sep 16 th, as seems to be indicated ), a UT time of 09h41m32.9s with an observed position as follows:

    S 27°47'6 and E 048°34'8 for an account longitude equal to 48°40' (he found longitude equal to E048°45'). So this sharp Observer was definitely within 5 minutes in Longitude from his DR.... Whaooo !!!

    Some more examples ? :-)) ....


    Best Regards


    Antoine M. "Kermit" Couëtte
    ----------------------------------------------------------------
    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
    ----------------------------------------------------------------

       
    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