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    Re: Home made artificial horizon
    From: Larry G
    Date: 2013 Nov 21, 10:39 -0800

    Home made Horizons. All of these methods are, IMO, low accuracy. However, mechanically on the right track.

    A good simple AR: 8" sauce pan, dark bottom like Teflon and coffee. Fill the pan to a depth of 3/16" or so. Shallow water/coffee stabilizes fast, and a breeze will cause ripples, but not sloshy waves. I've used cookie sheets too. A nice large field of view. Get it level, fill with coffe to a shallow depth. This is good in calm conditions only - a good arrangement for night work. An inch deep and it will never settle. Small pan, shallow liquid. Yes, motor oil is good and messy, but stay shallow. Strong, opaque coffee is great. you might consider molasses, or dark Karo syrup too. if you warm the syrup it gets thin. Let it cool and it gets viscous, which is what we want.

    A first surface mirror on a 3-screw leveling device sounds good, but very, very difficult to level. Digital levels are nowhere near what you need. However, the way to level a first surface mirror is to set a ball bearing on the mirror, assuming that it's optically flat! 3/8" dia ball bearing, or larger. If doesn't roll you'll be far more accurate than even a good digital level. (ever see a pool table leveled? They watch the roll of the ball, not a 'level'.) I like a first surface mirror, and leveling it is a challenge. No $50 digi level will work nearly as well as a ball bearing. then, repeat your work. Turn the screws a bunch, and re-level the mirror between multiple readings and average your results. with 8-10 repetitions you'll see how good you and the mirror are.
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