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    Re: slide rule sight reduction accuracy
    From: Gary LaPook
    Date: 2009 Jun 19, 04:05 -0700

    Paul Hirose wrote:
    > Regarding the Bygrave simulation, it can be done if I know the rules. 
    > For instance, azimuth is obtained by taking an arctangent, but that 
    > function yields a result between -90 and +90. There must be some rule to 
    > convert that to the range 0 to 360.
    But to do a simulation you do not need to get to the step of converting 
    Az to Zn since the Hc is computed from Az not from Zn.
    In a simulation, watch out for the special case where Az is greater than 
    85º since Hc becomes very sensitive to Az in that range and even 
    rounding up or down half a minute can make a significant change in Hc.
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