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: lunars with and without altitudes
    From: Alexandre Eremenko
    Date: 2006 Nov 14, 11:17 -0500

    
    Henry,
    Yes, this is one of the main points.
    I do not believe that the method is practical.
    (Of course an experiment is needed to decide.
    But I will be very surprised if it will be shown
    that the method can be useful in ANY real situation).
    
    Indeed, the expected accuracy is estimated as 0.5
    of a degree in the best case (ideal conditions, ideqal
    observer, ideal sextant, moon almost in zenith).
    
    And to achieve this degree of accuracy, the method still
    requires either altitudes of a DR position within
    a degree or so of the true position.
    
    Thus the strong version of the method (no altitudes no chronometer)
    will not work almost certainly.
    Still the weak version can be discussed (with altitudes but no
    chronometer). But why is it useful at all? There are better
    methods of finding latitude with sextant only, not using the Moon.
    
    I repeat that o nly experiment can decide, but I will be very
    much surprised if an experiment will give a positive
    (=sometimes useful) result.
    
    Alex.
    
    On Tue, 14 Nov 2006, halboth wrote:
    
    >
    >
    > Hi Alex,
    >
    > My whole point, of course, being the accuracy of the DR Position and the
    > "approximate" GMT. The simple fact is that, if you have confidence in your
    > DR, there really may be little point in considering a Lunar Observation -
    > given the potential inaccuracies of the latter, it may simply serve to
    > confuse the issue. Better advice might be to keep the lead going and to
    > maintain a sharp lookout, remembering always the four (4) Ls of navigation,
    > i.e., Latitude + Longitude + Lead + Lookout.
    >
    > Regards,
    >
    > Henry
    >
    > ----- Original Message -----
    > From: "Alexandre E Eremenko" 
    > To: 
    > Sent: Tuesday, November 14, 2006 8:55 AM
    > Subject: [NavList 1710] Re: lunars with and without altitudes
    >
    >
    > >
    > >
    > > There is one more little point:
    > > Moon's alt and star's alt are needed for refraction.
    > > Of course, one can compute these altitudes from the
    > > DR place, and approximate GMT,
    > > but then again the question of precision arises.
    > >
    > > Alex
    > >
    > >
    > >
    > > >
    > >
    >
    >
    > >
    
    
    --~--~---------~--~----~------------~-------~--~----~
    To post to this group, send email to NavList@fer3.com
    To unsubscribe, send email to NavList-unsubscribe@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