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    Re: An old Russian sextant certificate
    From: Modris Fersters
    Date: 2023 May 30, 22:31 -0700

    Dear Lars!

    The values in the certificate excatly matches the values derived from excentrity formula (except value at 70°, which may be simply misprinted). The difference between certificate values and calculated values are less than 1” (see the table below) . It seems to me the values in the certificate were calculated prom P and 2E rather than measured directly. 

    Main arc angle / Value in the certificate / Calculated value

    10°   5”   5,7”

    20°   11”   11,5”

    30°    17”    17,4”

    40°     23”     23,4”

    50°     29”    29,5”

    60°     35”    35,5”

    70°     36”    41,3”

    80°     47”    47,2”

    90°     53”    52,8”

    100°   58”    58,2”

    110°   63”    63,4”

    120°   68”   68,3”    

    I don’t understand how you got these 0,1’(6”) differences at 30°, 50°, 80° and 110°.

    Modris Fersters 

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