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    Re: Sight reduction formulae
    From: Alan S
    Date: 2011 Dec 1, 13:52 -0800


    If I'm understanding your problem-question correctly, try the following.

    1. From usps.org, download their sight reduction form SR98a. While there are numerous sight reduction forms, that's the one I use, being most familiar with it.

    2. From the lower section of this form, the part headed Intercept and Azimuth by the Law of Cosines method, note that where Lat and Dec are "opposite name", one +, the other -, when using a calculator to do the calculations, you need to insert a minus sign for Dec. This is done by hitting the Change Sign key on your calculator.

    3. The form, which included a Time Diagram is pretty straight forward.

    By the way, your description of the AH you built is quite interesting. A question re that, as I made one myself, but it does not seem to work at all well, possibly due to to small a mirror 4" x 6". Possibly I have a poor mirror, face of mirror not parallel or something of the sort.

    In any case, re the mirror that you used, did you happen to get "optically flat mirror glaass", or did you just get lucky with an ordinary piece of mirror glass. I believe the mirror you used is considerably larger than the one I have.
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