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: Averaging
    From: Jim Thompson
    Date: 2004 Oct 20, 16:52 -0300

    Fred's observer sextant altitude curves look a heck of a lot prettier what I
    get from the deck of our boat at anchor on a lunch hook.  My R-values
    certainly are not 0.9999 for a straight line fit!  Obviously I need more
    practice.
    
    I think I agree with Bill -- in real life on a small boat I would be happy
    with averaging 4-5 sights over 5 minutes.  My random observational errors
    are more likely to be much higher than any systematic error owing to
    nonlinearity in a body's motion, with the exceptions he noted.
    
    Jim Thompson
    jim2{at}jimthompson.net
    www.jimthompson.net
    Outgoing mail scanned by Norton Antivirus
    -----------------------------------------
    
    > -----Original Message-----
    > From: Bill
    > What did this beginner learn from the exercise?
    >
    > * Alex and Herbert are correct,the error is more pronounced for high
    > altitude bodies, and they are unacceptable targets for averaging
    > except for
    > all but last-ditch efforts, especially at meridian passage; even if
    > double-second-differences and problems with the operator holding
    > the sextant
    > vertical are discounted.
    >
    > * Shy away from averaging a body with a declination within 10d-20d of the
    > observer's latitude.  (If it would have trouble casting a
    > significant shadow
    > of the mast on the deck, leave it alone. This is cel nav SOP.
    
    
    

       
    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