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    Re: Jupiter and the Moon
    From: Hanno Ix
    Date: 2013 Jan 21, 17:48 -0800

    What do you think is the average error of a hooby-navigator on sea?
    I know there is a wide range, but please give me a range if you can.


    From: Frank Reed <FrankReed{at}HistoricalAtlas.com>
    To: hannoix---.net
    Sent: Monday, January 21, 2013 1:54 PM
    Subject: [NavList 22048] Re: Jupiter and the Moon

    Paul, you wrote:
    "I’d love to know if I missed something. Then I can stop blaming the Davis..."
    With a Davis plastic sextant, you can reasonably expect errors on the order of +/-2 minutes of arc for lunars. You MAY be able to do somewaht better, but it will take some care. In any case, it is what it. There are different capabilities for different instruments. There's no way that a plastic sextant with a 3x scope can achieve the same accuracy as a high-quality metal sextant with a 7x scope.
    As for the clearing of the lunar, the process you've described sounds a bit "fishy" to me. You're doing something that 'resembles' the process of clearing a lunar but it's not right. May I suggest that you try out the lunars CLEARING calculator on my web page here: http://reednavigation.com/lunars/lunars_v4.html.
    I have highlighted the word "clearing" here because you do not need the predicted lunars page which you may have assumed was the same thing. You don't need to do any interpolation. There are no issues of interpolation for shorter distances.
    After you have tested out some lunars using the clearing tool on my web site, if you would like to experiment more with doing your own clearing, I outlined a quick "calculator" method back in 2004 (good lord, eight years ago!) here:

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