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    Re: Making an artificial horizon, and leveling thereof
    From: Gary LaPook
    Date: 2011 Jan 21, 10:52 -0800
    As long as the tray is level enough that the liquid does not spill out it is level enough. The reason to use a liquid is that its surface will always be at right angles to the local "down" from the local gravity field. (This may not be exactly parallel to the celestial horizon but the differences is too small for us to worry about in doing celestial navigation.)

    gl

    --- On Fri, 1/21/11, Alan <alan202---.net> wrote:

    From: Alan <alan202---.net>
    Subject: [NavList] Re: Making an artificial horizon, and leveling thereof
    To: NavList@fer3.com
    Date: Friday, January 21, 2011, 9:39 AM

    Please coprrect me should my understanding be in error respecting "leveling" of an artificial horizon. I have used one purchased from Davis, the base containing water.

    Rregarding the liquid's surface being ruffeled by passing breezes, the clear glass shields, provided one doesn't drop them, they do not bounce well at all, or the colored plastic shields in conjuction with the side pieces that support them work quite well. Using the ah without shields can be tricky, as one needs absolutely still air.

    In any event, re "leveling", if I remember correctly, I read somewhere that this was NOT critical barring setting the thing up on a steep hillside, as "water, I suppose ditto for oil and or mercury, seeks it's own level". Is this, or is this not the case re using an artificial horizon?

    I've done sun shots with mine, in the spring and summer, standing in a reasonably level parking area at our apartment complex, taking sun sights several hours apart, that when plotted show quite small displacement between my calculated fix and GPS coordinates. Seems that orienting the ah properly is an important factor, as is being able to stand far enough away from the ah so as to be able to see the reflected and sextant suns.

    Comments, corrections please.

    Alan
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