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    Re: Trans Atlantic
    From: Gary LaPook
    Date: 2012 Nov 11, 10:14 -0800
    Have any of you tried adjusting the sights for movement of the vessel during the observation period using the "motion of the observer" tables that I posted?


    --- On Sun, 11/11/12, Antoine Couëtte <antoine.m.couette@club-internet.fr> wrote:

    From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
    Subject: [NavList] Re: TRANS ATLANTIC
    To: NavList@fer3.com
    Date: Sunday, November 11, 2012, 7:52 AM

    RE : [NavList] Re: TRANS ATLANTIC
    From: Mike Burkes
    Date: 11 Nov 2012 05:59
    Hi folks,regarding Altair site and using Hs 56 58.4:My initial "pinwheel" fix resulted in the three stars until I realised intercept was incorrectly plotted towards rather than away! Corrected fix eliminating Alpheratz,yielded 42 01.5 N 34 04.0W close to Greg's.
    Mike Burkes


    From London Heathrow on Nov 11th, 2012

    Hello Mike and Hello to all,

    Thanks for your last post, Mike.

    If eliminating Alpheratz on my side too, I am left with the following 3 azimuths and intercepts :

    ALPHERATZ i = -5.8 (A) NM , Z = 083°0 (REMOVE)
    ALTAIR i = -2.1 (A) NM , Z = 184°0 (KEEP)
    KOCHAB i = +0.2 (T) NM , Z = 338°4 (KEEP)
    MOON UL i = +1.5 (T) NM , Z = 121°6 (KEEP)

    Observed position has now become in Azimuth 060° and at distance of 3.4 NM from DR Position, with a LOP's dispersion of 0.2 NM, which would be excellent.

    At the Time (is it 17:56:20 LT ?) when DR position is N 42°00'0 W 034°10'0 , the Observed Position would be shifted 1.7 NM to the North and 3.0 Miles to the East (i.e. 3.6' of Longitude to the East) and would become N 42°01'7 W 034°06'4 (again very close to previous determinations from Greg and Mike).

    While I am relying on computations (almost) throughout, the main reason for the differences between our resulting fixes would probably come from the fact that Greg and Mike you seem to get your own positions through reading them from your hand-plotted charts.

    HOWEVER ...

    ... HINT ! As discussed in the past, there should be NO reason to eliminate Alpheratz unless for excellent reasons which I have not read about in this thread. I keep advocating that our position should rather remain (close) to our previous determination, i.e. N 41°59'7 W 034°13'4 .

    The only "key" to progress into a reliable knowledge of each individual LOP Quality here would be to know a GPS position and time around the time of observations, from which we could accurately time carry backwards/forwards in time the accurate Observer's position at the time of each specific sight.


    Same question also holds for your OCT 22nd, 2012 Fix.

    Best Regards to all

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