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    Re: A question for the geodisists
    From: Gary LaPook
    Date: 2013 Dec 17, 21:26 -0800
    No I can't, that is the question I am asking the denizens of navlist.

    gl



    From: Alexandre Eremenko <eremenko@math.purdue.edu>
    To: garylapook@pacbell.net
    Sent: Tuesday, December 17, 2013 7:02 PM
    Subject: [NavList] Re: A question for the geodisists


    This is a long article about geodesy in general.
    Could you point the place in this article which on your opinion
    explains the reason of disagreement in coordinates?
    
    Alex.
    
    > Well, this pretty explains why.
    >
    > http://en.wikipedia.org/wiki/Geodesy
    >
    > gl
    >
    >
    >
    >
    > ________________________________
    >  From: Chris Presmeg <0886045615{at}neomail.co.za>
    > To: garylapook---.net
    > Sent: Tuesday, December 17, 2013 12:56 PM
    > Subject: [NavList] Re: A question for the geodisists
    >
    >
    >
    >
    > ________________________________
    > 
    > What has Geodesy to do with it?
    > ----- Original Message -----
    >>From: Gary  LaPook
    >>To: CHRISTOPHER PRESMEG
    >>Sent: Tuesday, December 17, 2013 1:07  PM
    >>Subject: [NavList] A question for the  geodisists
    >>
    >>
    >>________________________________
    >> On July 2, 1937 Amelia Earhart was attempting to find Howland island.
    >> Her  navigator, Fred Noonan, was using celestial navigation to fly the
    >> standard  single line of position landfall approach to the island. (see:
    >> https://sites.google.com/site/fredienoonan/discussions/navigation-to-howland-island
    >>  )
    >>
    >>
    >>The  Pacific Sailing Directions (1885) gives the location of Howland as
    >> 0° 49'  north, 176° 40' west. Bowditch (1920) gives it as 0° 49' 00"
    >> north, 176° 43'  09" west. Bowditch (1938) gives it as 0° 48' north,
    >> 176° 38' west. This is  still listed as the correct coordinates in H.O.
    >> 126.
    >>
    >>
    >>Some  have argued that Noonan was working with the old coordinates and
    >> was aiming  for 0° 49' 00" north, 176° 43' 09" west and so missed the
    >> island by about five  nautical miles. However, the correct coordinates
    >> were given on the June 1937  edition of the local chart, 1198, so we know
    >> that the correct coordinates had  been found sometime prior to Earhart's
    >> departure from the states so I would  think that the updated information
    >> would have been provided to her,  considering that the orders to assist
    >> her came directly from the White House  and the importance of the correct
    >> information would have been apparent to  anyone.
    >>
    >>
    >>
    >>I  have looked at Howland on Google Earth and it now appears that it has
    >> moved to  the east another mile! And the coordinates found on the most
    >> recent chart now  show it also at 0° 48' 00" north, 176° 37' west, one
    >> mile east of he published  location. How does the island keep moving? If
    >> this is the true location then  Noonan may have been aiming another NM
    >> too far to the west. There is a note on  the newest chart that says:
    >>
    >>
    >>So  it appears that the most recent movement resulted from changing the
    >> datum to  WGS 84 but it seems to me that an adjustment of an entire mile
    >> to the east is  very large compared to other such shifts. So, if Noonan
    >> was using the old  coordinates would he have been aiming six NM west or
    >> just five? And I think  that I remember this correctly, that the geodetic
    >> gratical used for map making  places the landmarks where they would be
    >> placed by celestial navigation. So if  the island really is a at 176°
    >> 37' west then this might help explain why they  couldn't find the island.
    >> I thought that the greatest difference between the  geodetic and the
    >> geographic coordinates, as far as celestial navigation is  concerned, is
    >> in latitude and that changing to WGS 84 wouldn't have such a  large
    >> effect on longitude. Can someone explain how shifting from one datum to
    >> another would cause this type of error in the celestial navigation.
    >>
    >>
    >>
    >>
    >>
    >>
    >>gl
    >>
    >>
    >>
    >>Attached File:
    >>
    >>(img/125785.howland
    >   pages from 1920 american_practical_navigator_an_epitome.jpg: Open  and
    > save)
    >>
    >>Attached File:
    >>
    >>(img/125785.howland
    >   position_page_1.jpg: Open and  save)
    >>
    >>Attached File:
    >>
    >>(img/125785.howland
    >   position_page_2.jpg: Open and  save)
    >>
    >>Attached File:
    >>
    >>(img/125785.howland
    >   ge.jpg: Open and  save)
    >>
    >>Attached File:
    >>
    >>(img/125785.howland
    >   chart 83116.pdf: Open and  save or View  online)
    >>
    >>
    >>View and reply to this message:
    > http://fer3.com/arc/m2.aspx?i=125785
    > View and reply to this message: http://fer3.com/arc/m2.aspx?i=125799
    >
    > View and reply to this message: http://fer3.com/arc/m2.aspx?i=125803
    >
    >
    >
    >
    
    
    View and reply to this message: http://fer3.com/arc/m2.aspx?i=125806


       
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