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    Re: determination of longitude and the prime vertical
    From: Giuseppe Menga
    Date: 2007 Apr 16, 13:56 +0200
    Dear Jean-Philippe
    Anyone interested im my program for ephemeris, sight reduction and position estimation can find a copy at the site www.syco.it/temp/Ephemeris.rar
    Giuseppe Menga
    ----- Original Message -----
    Sent: Saturday, April 14, 2007 10:38 PM
    Subject: [NavList 2565] Re: determination of longitude and the prime vertical

    Hi Giuseppe,
    I would appreciate very much your sending me a copy of your programme; Thank you in advance.
    Best regards

    Giuseppe Menga <menga@polito.it> wrote:

    Dear George:
    I checked your data with a program built by me, which is based on Swiss
    I got the following results
    G.H.A 131° 9.90' decl. 15° 9.49' with a difference of 0.1' for the G.H.A.
    and 0.01' for the declination.
    We can both be satisfied of our programs!
    Giuseppe Menga
    P.S. by the way, if someone is interestes I will be happy to share my
    ----- Original Message -----
    From: "George Huxtable"
    Sent: Thursday, April 12, 2007 4:45 PM
    Subject: [NavList 2556] Re: determination of longitude and the prime

    > I hope Geoffrey Kolbe's respose, with Bill's reply, show that the problems
    > that Bill raised in Navlist 2550 are now resolved..
    > But a minor matter cropped up in that mailing that worries me a bit.
    > Bill quoted some predicted Sun positions, that had come from Andres Ruiz'
    > website.
    > I will refer just to that first set of numbers from his mailing, as
    > follows-
    > | Date: 1 May, 2007
    > | UT: 20:41:45
    > | Position: N40 W60
    > | Hc: 24d 00!2
    > | Az: 270.00
    > | LHA: 71d 09!5
    > | dec: 15d 09!5
    > I don't have a 2007 Nautical Almanac. But I have compared those numbers
    > with
    > my own predictor, held on a pocket calculator, which differs slightly.
    > That gives a Sun position, at 20:41:45 GMT on 1 May 2007 of 15 deg 09.5'
    > N,
    > exactly as Bill gave it, but a GHA of 131deg 09.8', and so with a long of
    > 60deg W, a LHA of 71deg 09.8', just 0.3' more than the figure Bill stated.
    > That difference isn't a large one, but to me it's a bit of a worry,
    > depending on which of us is in error. I expect the Sun predictions of that
    > program to be generally well within a millidegree. One might expect
    > divergences of 0.1', as a result of rounding errors, but not more. If my
    > program is out by that amount I need to investigate why.
    > So I wonder if Bill will kindly recheck that figure, and ask anyone with a
    > current Nautical Amanac or computed equivalent, to provide a value for Sun
    > GHA at that moment, please.
    > George.
    > contact George Huxtable at george@huxtable.u-net.com
    > or at +44 1865 820222 (from UK, 01865 820222)
    > or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    > >

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