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    Re: Lunar Distances with Alex's SNO-T
    From: Alexandre Eremenko
    Date: 2006 Nov 1, 19:47 -0500

    Can you suggest a testing range
    in Greater Lafayette area where we can perform
    Frabk's laser testing. (I will buy a laser level
    for this purpose). We need a 500 feet flat place
    with a table on one side and no people walking.
    I see no other way to resolve the controversy with index.
    Today experimented again with Frank's sextant.
    IC from moon +0.65 4SD=66.7
    True 4SD=65.6 (but no more than 66.0 in any case!)
    IC from stars +0.2
    Then shot Moon - Altair 4 times and got as perfect
    sequence if IC=+0.2. Here it is
    Errors: -0.1, +0.1, 0.0, +0.2
    I consider this a strong argument agaionst the Moon method.
    Then shot again Altair-Deneb: 38d00'7 (No IC applied)
    while the truth is
    38d00.2, so I have the usual overshot.
    But in this case, IC from the Moon method givews the good
    Thus I have a well established pattern:
    IC from stars is about +0.2 or +0.3
    and this works well with the Lunars.
    IC from Moon is about 0.6 to 0.7 and this works
    well with star distances.
    The only way to solve this contraversy
    is to try the laser test.
    On Wed, 1 Nov 2006, Bill wrote:
    > >> Alex has in the past looked poorly on natural horizon IE/IC.
    > >
    > > 1. Natural horizon is rarely so well defined as
    > > a star or a Sun's edge.
    > > 2. The Russian book "Precision of astronomical observations"
    > > says that (based on large statistics) IC from horizon is much less
    > > precise than that from the Sun.
    > I'm sure the author of the study had performed more trials than I have, but
    > the standard deviation (n-1) of my natural horizon IE checks--from a
    > boat--are every bit as good as those of the sun from a chair.
    > They do help to verify that my vertical sun IE checks (I believe due to
    > astigmatisms) are too high.  Currently on the arc 0.75' on for sun,
    > 0.3'natural on for horizon.  This syncs up with vertical sun IE checks done
    > with glasses.
    > I have confirmed this by standing on the Soldier's Home Road overpass (over
    > Sagamore Parkway) looking east and using flat-top buildings, corn-refinery
    > stacks and towers as well as the distant tree line.  A bit closer than I
    > would like, but it should not cause more than a 0.1' error.
    > It would appear that a good bit of the problems I have with consistent
    > undershoots is using a sun-determined IC that is too high.
    > >
    > >> You have noted in the past that a bit of side error may be useful
    > >
    > > Later Frank corrected this statement. It can be useful for IC
    > > checks with stars. But it is certainly harmful with Sun or Moon
    > > checks.
    > Understood, especially with your 4SD requirements.
    > Bill
    > >
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