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    Re: A practice round of stars
    From: Alan S
    Date: 2013 Mar 6, 15:42 -0800


    Re your round of stars, finally found the time and inclination together, to "take a shot" at them. The following are the results I obtained, along with some comments/questions, should you care to read through them and respond.

    1. You had a ZD of -8. Dividing 109D 40M by 15, I get -7.33, which would become -7. Am I mistaken? I used your ZD.
    2. I reduced the sights using Nautical Almanac Daily Pages, the USPS Sight Reduction Form, LOC Method, and the USPS Constant Latitude Sheet for plotting.
    3. I used your DR, without compensating for ships movement along the course and at speed you indicated. This will introduce a degree of error, a small one I think, though some error. Am currently redoing the plot, taking into account ship's movement, along a course of 037 True, {at} 11.6 knots. This might correct errors or it might introduce some new ones, arising from my plotting skills or the lack thereof.
    4. I assume that times indicated are Watch Times, no watch error indicated.
    5. Re the first plot, I got 2 triangles, one fairly large, the other falling within the first. Position fixes within triangles, bisecting sides and so forth, fall OUTSIDE the triangles. Re larger triangle, fix coordinates obtained 8D 44.5M North x 109D 57.5M East. Coordinates obtained from second triangle are 8D 56.5M North x 109D 51.5M East. If you like, I could probably scan sight reductions and plot, then email to you.

    In any event, the following are the sight reduction numbers I obtained, in the following order. LHA, Ho, Hc, Dec., Zn

    Moon, LL 73D 20.7M, 14D 14.5M, 14D 20.8M, 11D 15.2M South, 259D

    Jupiter 320D 38.5M, 50D 34.6M, 50D 14.6M, 20D 47.7M North, 69D

    Rigel 307D 50.5M, 35D 25.3M, 35D 19.2M, 08D 11.4M South, 98D

    Capella 308D 00.3M, 32D 17.0M, 32D 12.7M, 46D 00.6M North, 44D

    Fomalhaut 46D 16.4M, 31D 09.9M, 31D 13.6M, 29D 33.2M South, 240D

    Otherwise, hope all goes well with you and yours. Let me know how my efforts strike you, time and inclinations allowing.



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