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    Re: Raw data for bubble
    From: Bill B
    Date: 2007 Mar 10, 18:41 -0500

    Peter Wrote
    > This is a new method for me. I calculate the 'Change of Altitude in 5
    > Minutes of Time' as a function of azimuth and latitude. The main thing
    > is to end up with the actual (apparent) rise or fall as a line, used
    > to compare the sights made against. They are plotted on graph paper,
    > altitude vertically, time horizontally. If the sights were perfect
    > their slope would be parallel to the calculated slope. The extent that
    > they do not fit that slope is an indication of error, but only of
    > random error.
    Does this look like the method you use to calculate slope?
    Delta H (rate of change in arc minutes) per minute of time  (divide by 60
    for degrees)
    Delta H = 15 * cosine latitude * sine azimuth (or its supplement)
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