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    Re: Instrument Error
    From: Fred Hebard
    Date: 2005 Apr 24, 17:08 -0400

    I mentioned that my sun-moon lunars were markedly inferior to other
    lunars.  Here are some data on that.  For a while, I thought I was
    failing to converge the objects in the center of the glass, so I bought
    a Russian 7x (6x ?) inverting scope with wires in the field of view, so
    that I could center the objects (and get greater magnification than
    offered by my 4x star scope).  This didn't seem to help, as indicated
    below.  In general, the sun lunars show a gap of about 1.2' to 1.4' of
    arc, while the star and planet lunars show no gap.  The one difference
    that remains to be explored is that the sun lunars have much larger
    distances than the star lunars, so that arc eccentricities or failure
    to maintain the sextant in the plane of observation may be occurring.
    I haven't used the inverting scope very much yet, so I'm far from
    proficient with it.  But the bias appears to persist with it, and
    appears to be .
    Date    Telescope       Objects Mean(clrd
    D)      N(delarc')      Mean(delarc')   StdDev(delarc')
    09/22/2004      4xGalilean      Moon,Antares    38      2       0.1     0.38
    04/18/2005      7xinverting     Moon,Jupiter    58      7       0.5     0.21
    04/20/2005      4xGalilean      Moon,Jupiter    21      6       -0.1    0.28
    10/06/2004      4xGalilean      Moon,Venus      49      7       -0.2    0.26
    10/07/2004      4xGalilean      Moon,Venus      38      6       -1.1    0.23
    09/20/2004      4xGalilean      Moon,Sun        80      6       1.2     0.37
    09/21/2004      4xGalilean      Moon,Sun        92      6       1.3     0.49
    10/05/2004      4xGalilean      Moon,Sun        97      6       1.4     0.15
    10/06/2004      4xGalilean      Moon,Sun        87      8       1.2     0.34
    10/08/2004      4xGalilean      Moon,Sun        66      10      0.7     0.38
    11/07/2004      4xGalilean      Moon,Sun        62      6       1.7     1.28
    04/16/2005      7xinverting     Moon,Sun        93      6       1.4     0.15
    04/17/2005      7xinverting     Moon,Sun        103     8       1.2     0.24

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