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    Re: Haversines with Logarithms
    From: Gary LaPook
    Date: 2020 Oct 14, 11:01 -0700

    Don't be too hard on that poor clerk since it can take a very long time to find errors in navigation tables.

    I posted this in 2008: 


    On Tue, Oct 21, 2008 at 1:54 AM, Gary LaPook <glapook---.net> wrote:
    Gary LaPook writes:

    Although the page numbering is the same in my 1970 edition of H.O 249 mine does not contain the error that you identified. I checked the online version of H.O. 249 at:  http://www.nga.mil/portal/site/maritime/?epi_menuItemID=8755b5dbee96c4327b2a7fbd3227a759&epi_menuID=35ad5b8aabcefa1a0fc133443927a759&epi_baseMenuID=e106a3b5e50edce1fec24fd73927a759

    and found the same error on those two pages.

    Last November 28th I posted the messages below and it now appears that they have corrected on the online edition the errors I had pointed out to them at that time. The contact information in that exchange might be useful in bringing this new error to their attention.


    "I recently posted a link to the government web site where you can
    download copies of navigational publications including H.O 249. I
    quote below the email I sent to that site:

    "Dear Sir:

    "Quite by chance I noticed an error in the on line edition of HO 249
    volume 2. I then looked for similar errors and found that there is a
    systematic error in both volumes two and three. For example, on page 5
    of volume 2 covering latitude 0º in the first column covering
    declination of 15º at LHA 89 the altitude given is 00-58'; for LHA 90
    the altitude is given as 00-00'; and for LHA 91 the altitude given is
    00-58' which is the same value as given for LHA 89! This is
    mathematically impossible. The problem is that the altitude for LHA 91
    should be negative 00-58'. The systematic error found all across the
    tables up to at least latitude 39º is that  all of the last positive
    altitudes tabulated should all be negative altitudes! This is also
    true for the values given for contrary name declinations. For example
    on page 163 of volume 2 covering latitude 27º in the first column for
    0º declination tabulated for LHA 91 an altitude of 00-53'; for LHA 90
    an altitude of 00-00'; and again at LHA 89 an altitude of  00-53'. The
    altitude for LHA 91 should be negative 00-53'.

    "I compared these examples with my printed copies of these tables
    printed in 1970 and these errors do not appear in the printed version
    which correctly label these altitudes as negative altitudes."


    Gary LaPook

    Gary LaPook writes:
    I recieved the following email from the government website that had
    published H.O 249 with errors.

    "Mr. LaPook

    Thank you for bringing this error to our attention. It seems that the
    Sight Reduction Table generation code improperly formatted entries
    beginning with -0, inserting 00 instead.

    I am in the process of manually updating the electronic publications,
    which will be posted to our Web site in the very near future.

    The errant publications were originally produced and posted to our Web
    site in 1999. Which mean that, in their 8+ years of service, you are
    the first and only user to notice the error!


    Tim Doherty
    Office of Global Navigation/Technology
    National Geospatial-Intelligence Agency

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