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    Re: Precision of lunars
    From: Alexandre Eremenko
    Date: 2007 Apr 15, 10:18 -0700

    Observations in March-April 2007.
    
    SNO-T from my balcony IC=-0.5 (constant, measured at least once a
    day).
    Reduction with Frank's calculator, temperature and pressure was taken
    into account. No correction was used for prizmaticity of filters;
    after a careful investigation it was found to be less than 0.15'
    for all filter combinations.
    The IC actually varies a little, but this variation seems to depend on
    the method of measuring IC, rather than on time. 3 or 4 years of
    experience
    with this sextant show that IC remains constant unless I transport it
    by
    car, train or airplane, or do some adjustment.
    Using different methods I always obtain IC between -0.4 and -0.6 so I
    use the average.
    
    I post ALL my observations
    from March 20 till now, not trying to choose the
    best or the worst or "typical".
    
    Total 85 shots of lunar distances
    in 20 series (usually 4-6 each).
    Average error over all shots is 0.07 (thus the systematic
    bias seems negligible).
    Sigma over all shots is 0.26.
    
    Error distribution for individual shots:
    41 with error less than 0.1
    19 with error in the interval (0.1-0.2)
    11 with error in the interval (0.2-0.3)
    5 with error in the interval (0.3-0.4)
    7 with error in the interval (0.4-0.5)
    2 with error in the interval (0.5-0.6)
    (of the total of 85)
    
    Error distribution of series:
    10 with error less than 0.1
    4 with error 0.1-0.2
    5 with error 0.2-0.3
    1 with error 0.2-0.4.
    (of the total of 20 series)
    
    Here is the list of all series:
    
    April 13, Sun at 53d:
    0.1, -0.2, -0.5,  -0.3, -0.3;    aver=-0.24, sigma=0.22
    0.1, 0.0, 0.0, 0.0, 0.2;         aver= 0.06, sigma=0.1
    April 3, Aldebaran at 126d (full Moon, too bright, was not
    sure about the correct limb):
    0.4, 0.3, 0.2, 0.3, 0.2;         aver=0.28   sigma=0.08
    0.3, 0.6, 0.4, -0.2, 0.6, 0.4, 0.8; aver=0.4, sigma=0.3
    April 3, Pollux at 73d:
    0.0, -0.1, -0.1, -0.1;           aver=-0.07, sigma=0.05
    April 2, Venus at 137d:
    0.3, 0.0, 0.5, 0.4;              aver=0.3, sigma=0.2
    0.3, 0.2, 0.5, 0.2;              aver=0.3, sigma=0.14
    0.0, 0.0;                        aver=0.0, sigma=0.0
    0.1, 0.0, 0.1.                   aver=0.06, sigma=0.06
    April 2, Aldebaran at 115d:
    0.1, 0.1, 0.1, -0.3, 0.2, 0.0;   aver=0.03, sigma=0.17
    March 29, Sun at 139d (limit of sextant scale!)
    0.4, -0.5, 0.1, -0.5, -0.1;      aver=-0.12, sigma=0.4
    March 29, Venus at 102d:
    0.0, 0.1, 0.1, -0.1, 0.3;        aver=0.08, sigma=0.15
    March 29, Saturn at 10d:
    -0.1, 0.1, 0.1, 0.3, 0.1, 0.3.   aver=0.13, sigma=0.15
    March 29 Aldebaran at 79d
    0.2, 0.0, -0.1, 0.2              aver=0.07, sigma=0.15
    March 26, Venus at 70d:
    -0.2, 0.1, 0.1;                  aver=0.0, sigma=0.17
    0.0, 0.1, 0.2, -0.2;             aver=0.0, sigma=0.17
    March 26, Aldebaran at 42d:
    -0.2, -0.1, -0.5;                aver=-0.26, sigma=0.2
    March 25, Venus at 58d:
    -0.2                             aver=0.2
    March 21, Venus at 7d:
    0.1, 0.2, 0.2;                   aver=0.16, sigma=0.06
    March 21, Aldebaran at 30d:
    -0.1, -0.2, 0.2, 0.1, -0.5, 0.0; aver=-0.08, sigma=0.24
    
    
    Alex.
    
    
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