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    Re: CN in the GPS Age
    From: John Karl
    Date: 2007 Sep 29, 12:02 -0700

    
    Gary J. LaPook wrote:
    > That is the same question for which I have never gotten an answer. The
    > arrangement of tables in H.O.249 and H.O. 214 is much more convient,
    > often allowing you to do the entire round of sights with only one book
    > opening.
    > So who's bright idea was it to use LHA instead of latitude in H.O. 229?
    >
    > gl
    >
    >
    >
    > jhk wrote:
    >
    >
    > "Nonetheless, from what I've seen of the NavList, most members will know
    > most everything in the book -- and then some.  Which brings me to the
    > one question I asked in the book that I can't figure out myself:  Why
    > are the tables in H.O. 249 and H.O. 229 ordered differently?  I much
    > prefer H.O. 249's order because latitude changes slowly at sea, while
    > we're always skipping around in LHA"
    >
    >
    >
    > jhk wrote:
    >
    > > Hi Folks,
    > >
    > > Frank ask for a little info on my book.
    > >
    > > It all started from fairly complete notes that I had made for a couple
    > > of short courses on CN.  Then I decided to expand them even more,
    > > just in case other short-course opportunities cropped up.  That's when
    > > I got curious about how other authors treated the subject.  I was
    > > surprised to learn how different our approaches were.  Most all
    > > authors had incorrect (or misleading) explanations of the "assumed
    > > position" used in the St. Hilaire method (or they didn't attempt an
    > > explanation at all), naive or incorrect figures, explained only one or
    > > two kinds of sights, skipped lunars, omitted any computer
    > > applications, had no historical perspective, and had no exercises for
    > > the reader's practice and confidence building.
    > >
    > > So I decided it might be worth while to put my notes into book form.
    > > I covered all of the above topics, while making the book topically
    > > graduated, allowing the beginner to do a full sight reduction by page
    > > 40.  The book is really all about the same level with only one
    > > equation (the cosine law, naturally) used for all nine types of sight
    > > reductions.  But the 72 exercises are graduated in difficulty, started
    > > with only high school math and ending with asking the reader to show
    > > that my exact lunar-distance clearing equation reduces the commonly
    > > used 2nd-order power series.  So I hope, perhaps naively, that the
    > > book has something for everyone.
    > >
    > > Nonetheless, from what I've seen of the NavList, most members will
    > > know most everything in the book -- and then some.  Which brings me to
    > > the one question I asked in the book that I can't figure out myself:
    > > Why are the tables in H.O. 249 and H.O. 229 ordered differently?  I
    > > much prefer H.O. 249's order because latitude changes slowly at sea,
    > > while we're always skipping around in LHA.
    > >
    > > At the risk of being too wordy on the NavList, here's the contents of
    > > the book:
    > >
    > > Celestial Navigation in the GPS Age
    > >
    > > 1.  Introduction.  The Heroic Era, The Story Retold.
    > > The Fundamental Idea:  An Ancient Observation, the Key concept, The
    > > Mariner's Angle.
    > > The Equal-Altitude Line of Position: The 3-D Picture, The Limitations
    > > of Mechanical Methods, The Only Solution.
    > >
    > > 2.  Plotting the Celestial Navigation LOP.
    > > Coordinates:  Latitude and Longitude, Greenwich Hour Angle and
    > > Declination.
    > > The Navigation Triangle:  Sun and Earth, The Local Hour Angle, Azimuth
    > > Angle and Azimuth.
    > > Three Plotting Methods:  The Concept, Plotting Variables.
    > >
    > > 3.  The St. Hilaire Method.  The Captain's Idea, The Straight-line
    > > Approximation, The Error, Why St. Hilaire?
    > >
    > > 4.  The Nautical Almanac - an Overview.  The Daily Pages, The Altitude
    > > Corrections.
    > >
    > > 5.  Sun Sight Reductions.
    > > Using Direct Calculation:  Attitude Corrections, The GHA and
    > > Declination, The GHA and Declination Increments, The LHA, The Sketch,
    > > The Triangle Solutions.
    > > Using Tables: The Solution using H.O. 249, The Solution using H.O. 229.
    > > Four Examples of Sun Sights.
    > >
    > > 6.  Sights of Other Celestial Bodies:  Availability, The Planets, The
    > > Stars, Star Sights by Direct Calculation,  Star Sights by H.O. 249,
    > > The Moon.
    > >
    > > 7.  Special Sights.  Polaris, Meridian Sights, Latitude without
    > > Meridian Shots or UT, Latitude and Longitude from Meridian Sights,
    > > Longitude from Altitude and Latitude, Time from a Lunar LOP and a Star
    > > Fix, Position without St. Hilaire.
    > >
    > > 8.  Lunar Distance Sights.  The Concept, Taking a Lunar Sight, The
    > > Distance Clearing Concept, Clearing the Lunar Distance, The Sight
    > > Reduction,  A Lunar Example, Accuracy, So Why Lunars Today? Other Lunars.
    > >
    > > 9.  The Altitude Observations.
    > > The Sextant:  The Horizon Mirror, The Telescope, Telescopes with
    > > Traditional Horizon Mirrors.
    > > Sextant Checks and Adjustments: The Telescope, the Index Mirror, The
    > > Horizon Mirror, Index Error, Backlash, Sextant Arc Error.
    > > Sextant Observations: Observations at Home,  Taking a Sight, Averaging
    > > Sights.
    > > Altitude Corrections:  Dip, Refraction, Upper and Lower Limbs, Parallax.
    > >
    > > 10. Operations at Sea:  Celestial before GPS, Celestial with GPS,
    > > Those Special Sights, Plotting, Estimated Positions and Running Fixes,
    > > Special LOP Orientations, Great-Circle Sailing, Time, Accuracy.
    > >
    > > 11.  Tables, Calculators, and Computers - the Debate:  Sight Reduction
    > > Tables, Calculators and Computers.
    > >
    > > 12.  Insights from the Navigation Triangle:  Equivalent Triangles, The
    > > Azimuth Rules, Understanding Inspection Tables, Special Cases of the
    > > Azimuth Equation.
    > >
    > > 13.  Exercises for Understanding and Confidence:  Sight Reduction and
    > > the Navigation Triangle; Navigational Astronomy; Courses, Distances,
    > > and Charts; Lunar Distances; Computer Programming.
    > >
    > > Appendices:  A. Navigation Triangle Formulae,  B. Calculator
    > > Keystrokes,  C. The Nautical Almanac,  D.  Sight Reduction Tables,  E.
    > > Sight Reduction Worksheets,  F. Concepts in Plane Trigonometry,  G.
    > > Sextant Arc Error Tables,  H. Dip Short of Horizon,  I. A Brief
    > > History of Navigation,  J. Annotated Bibliography
    > >
    > > .....  John Karl
    > >
    > >
    > >
    > >
    > > >
    
    
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