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: averaging devices on sextants
    From: Ken Gebhart
    Date: 2004 Oct 8, 21:10 -0500

    Again, I agree with your comments.  I was referring to using an averaging
    mechanism to accomplish the task.  Averaging mechanisms have their own
    accuracy specifications of up to four minutes of arc, which is added to the
    accuracy of the sextant itself.  Thus accuracy of the entire system is
    worse. Certainly manual averaging of many individual sights by the navigator
    himself would improve overall results
    ----- Original Message -----
    From: "Alexandre Eremenko" 
    Sent: Friday, October 08, 2004 9:06 AM
    Subject: Re: averaging devices on sextants
    > Thank you to all for interesting information in reply
    > to "Averaging". There is one point on which I think additional
    > comment is necessary:
    > On Thu, 7 Oct 2004, Ken Gebhart wrote:
    > > The idea of averaging sextant readings using a marine sextant,
    > > (ie. instead
    > > of using a bubble), really has no basis because acceleration
    > > has no effect
    > > on it.
    > The procedure of averaging observations using a marine sextant
    > is recommended by many books and manuals, from XVIII century
    > to these days.
    > It is not specific to bubble horizons or effects of acceleration.
    > It is also used on land.
    > The purpose of this procedure is to increase precision.
    > In fact this is a standard procedure increasing accuracy of
    > ANY scientific measurements.
    > The theoretical foundation of this procedure lies in
    > the "Method of Least Squares" by Gauss. The most
    > comprehensive discussion
    > in the context of practical astronomy
    > of this theoretical basis is contained in the last chapter of
    > Chauvenet's 2-nd volume.
    > The specific of aerial observations is that the random error
    > coming from acceleration is very large, and the averaging has
    > to be done quickly. That's why they have a built-in mechanism,
    > integrator, that does it automatically.
    > Alex.

    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