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    Intercept and distance
    From: David C
    Date: 2016 Jun 15, 20:58 -0700

    I created a pseudo observation by determining the altitude of the Sun using an app on my phone and reading the time on my PC. I have reduced the sight by two methods. The intercepts are:

    AP 3270  15'

    Cosine formula/trig calculator 13'

    Is this difference to be expected or does it indicate an error on my part?

    Because I know the actual position (I measured it with my phone) and distances are small I reasoned that I could calculate the distance between the assumed and actual positions by plane trig. This distance should equal the intercept(????). Here is my calculation:

    lat 41

    dlong 20.7'     departure 15.6'  (from dlong*cos(lat))

    dlat 6.4'

    Applying pythagoras the distance is 17'.

    I have three different numbers 13, 15 & 17. Have I made an error in my calculations or is this magnitude of differences to be expected?  Maybe I am confused about the intercept, the distance or departure?

    Thanks for your comments.

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