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RE : http://www.fer3.com/arc/m2.aspx?i=116516
[NavList] Re: Any "on line" Star Position Computation available ?
From: cfuhb-acdgw---net
Date: 13 Jun 2011 11:42

Dear Paul,

Thank you for your contribution.

It is ( definitely ??? :-(( !!! ) looking like there is no on-line web site to compute Stars apparent coordinates with a precision better than the one usally required for classical maritime Cel-Nav.

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Thanks also for mentioning the VizieR access tool which I have been regularly using as well as the Simbad access Tool (http://simbad.u-strasbg.fr/simbad/).

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FK6 vs HIPNEWCAT

My mention of FK6 to Andrés was actually an "off-track/off topic" idea, as it simples addresses a different matter : is FK6 more accurate or less accurate than HIPNEWCAT publihed in the ICRS Frame ?

We know that HIPNEWCAT (i.e. HIPPARCOS 2007) is derived from the same "raw data" as HIPPARCOS 1997, but with better and improved physics modeling and mathematical algorithms.

If FK6 could be deemed better than "HIPPARCOS 1997" as their Authors claimed it then, I personnally would think that this might no longer be the case after HIPNEWCAT was published, for at least the following reason :

- To the best of my knowledge, FK6 was published a few years before our current IAU 2006 Precession (i.e. the P03 Precession Theory) was available. Therefore, when "building up" the FK6 Catalog for the Epoch 2000.0, its authors did not have at hand a Precession Theory as deadly accurate as P03 is nowadays (maximum linear error believed to be in the order of 1" per 1000 years).

I simply wish to get second thoughts on this specific subject (i.e. FK6 / HIPNEWCAT comparison) from however on NavList is knowledgeable on the accuracy of the current Star Catalogs.

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Thank you again, Paul and

Best Regards

Kermit

Antoine M. "Kermit" Couëtte

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