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: Artificial horizon question
    From: Peter Hakel
    Date: 2009 Apr 20, 14:16 -0700

    There is no dip correction for the height of eye in this case.  The index correction always needs to be made.  If you overlap the disks then there would be no semidiameter correction either.  However, I believe that more frequently than not people bring the disks to touch each other, in which you do have to correct for the semidiameter after you divide the (index corrected) sextant altitude by 2.


    From: "JKP@obec.com" <JKP@obec.com>
    To: NavList@fer3.com
    Sent: Monday, April 20, 2009 12:51:57 PM
    Subject: [NavList 8001] Re: Artificial horizon question

    Tnhnaks for your advice.  I'll see if I can check the parallelism as you describe.

    GTeorge, Thanks for your advice as well.  I will either get a piece of black glass (and devise a means of leveling it as I have read in past posteings) or at least try some sort of non-reflective treatment for the pan bottom.

    I don't particularly suspect that I'm getting a double image from the oil pan, however.  When sighting the sun, I use a colored cover over the artificial horizon pan, and different colored filters between my eye and the sun, and I get two distinctly colored images, say green from the sky and yellow from the pan.  It is these that can't seem to be brought very near each other horizonatally.  That is, until for one luck second they slip right over one another, and if I'm quick with the micrometer I can get my shot beforfe they agaion wobble apart.

    By the way, I had also meant to ask:  Should I ignore altitude correction when using an artificial horizon?  Clearly no correction for semi-diameter should be needed, because I am superimposing full discs of the sun and its reflection, center-over-center, rather than touching the upper or lower limb to the horizon.  But I guess I can't grasp the principle behind altitude correction sufficiently to decide whether it counts in this situation.


    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@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)