NavList:

----- Original Message -----

From: jean-philippe planas

To: NavList@fer3.com

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

JPP

Giuseppe Menga <menga@polito.it> wrote:

Dear George:
I checked your data with a program built by me, which is based on Swiss
Ephemeris.
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
program.
----- Original Message -----
From: "George Huxtable"
To:
Sent: Thursday, April 12, 2007 4:45 PM
Subject: [NavList 2556] Re: determination of longitude and the prime
vertical


>
> 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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