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    Re: help with sun sights
    From: Gary LaPook
    Date: 2011 Jan 16, 01:22 -0800
    I just added this to my website:

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    HINTS FOR MAKING YOUR BYGRAVE


    Print the cotan scale on photo paper. Print the cosine scale on ink jet  transparency film such as 3M made"Transparency film for Ink Jet Printers," stock number CG3480.

    To ensure that the two scales are printed at exactly the same scale remember that the cotan scale spans two cycles while the cosine scale covers only one cycle. To test the proper scale check that the cosine scale covers exactly one half of the cotan scale. An easy way to do this is to place the right hand end of the cosine scale on any value you choose on any line of the cotan scale then check that the left hand end of cosine scale, one line up,  lines up with the same value one line higher on the cotan scale. If they don't, then adjust your printer until they do. You can use plain paper for making this check, instead of the more expensive transparency sheet, by holding them up to a light.

    For increased durability you can seal each scale in 3M "Self-Sealing Laminating Pouches," stock number LS854-5G or -10G. When sealing the transparency sheet you must be careful to work slowly to smooth out any bubbles since the transparency sheet can trap bubbles.

    -----------------------------------------------------------------------------------------------------------

    --- On Sat, 1/15/11, Gary LaPook <glapook---.net> wrote:

    From: Gary LaPook <glapook---.net>
    Subject: [NavList] Re: help with sun sights
    To: NavList@fer3.com
    Date: Saturday, January 15, 2011, 11:49 PM

    We talked about this in the past, see prior posts at:

    http://www.fer3.com/arc/m2.aspx?i=114077&y=201010



    http://www.fer3.com/arc/m2.aspx?y=200904&i=107908

    gl

    --- On Sat, 1/15/11, Gary LaPook <glapook---.net> wrote:

    From: Gary LaPook <glapook---.net>
    Subject: [NavList] Re: help with sun sights
    To: NavList@fer3.com
    Date: Saturday, January 15, 2011, 11:37 PM

    I have to add that using H.O. 249 volume 2 and 3 is the same as using H.O. 229 but using H.O. 249 volume is different but easier once you know how it works. But volumes 2 and 3 cover all latitudes and all bodies up to 30° declination. This means that you can work the sun, moon, planets and 31 of the 57 listed stars. You can't use H.O. 249 volume 2 and 3 for 10 stars with high northern declinations or 16 stars with high southern declinations. Volume 1 though lets you use many of these additional stars but with a different procedure.

    I have complete sets of H.O. 249, H.O. 229, H.O. 214 and H.O. 218.

    gl

    --- On Sat, 1/15/11, Gary LaPook <glapook---.net> wrote:

    From: Gary LaPook <glapook---.net>
    Subject: [NavList] Re: help with sun sights
    To: NavList@fer3.com
    Date: Saturday, January 15, 2011, 4:43 PM

    H.O. 229 takes up a lot of space and is heavy and provides more precision than is actually needed for small craft navigation. H.O. 249, Sight Reduction Tables for Air Navigation,  is much more compact and the arrangement of the tables is more convenient. Both tables are used the same way (with the exception of the second differences correction for slightly greater accuracy for high altitude sights in H.O. 229 that you can skip if you choose) so if you can work one set of tables you can work the other. I suggest you download H.O. 249 from this site:


    http://msi.nga.mil/NGAPortal/MSI.portal

    (click on "Publications")

    print out a few pages and compare with your H.O. 229.

    You can check your work by having the Navy do the computations here:

    http://www.usno.navy.mil/USNO/astronomical-applications/data-services/cel-nav-data

    Since you are just getting started, and before you head gets polluted with these other complicated methods, I suggest you try the flat Bygrave slide rule which you can make for yourself at a cost of a few dollars with the printouts available here:

    https://sites.google.com/site/fredienoonan/other-flight-navigation-information/modern-bygrave-slide-rule

    https://sites.google.com/site/fredienoonan/other-flight-navigation-information/self-contained-long-term-celestial-navigation-system

    The Bygrave computes everything your need in less than two minutes and uses no batteries.

    gl

    --- On Sat, 1/15/11, Patrick Goold <goold{at}vwc.edu> wrote:

    From: Patrick Goold <goold{at}vwc.edu>
    Subject: [NavList] Re: help with sun sights
    To: NavList@fer3.com
    Date: Saturday, January 15, 2011, 2:15 PM

    Gary,
    I am using HO 229. 

    Patrick


    On Fri, Jan 14, 2011 at 10:22 PM, Gary LaPook <glapook---.net> wrote:

    "I am still unclear how to read the reduction tables. Thanks so much!"

    Which tables are you using?

    gl
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    --
    Dr. Patrick Goold
    Department of Philosophy
    Virginia Wesleyan College
    Norfolk, VA 23502
    757 455 3357

    Charles Olson: "Love the World -- and stay inside it."

       
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