NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: historical star coordinates
From: Peter Hakel
Date: 2012 Nov 6, 05:45 -0800
From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
To: NavList@fer3.com
Sent: Tuesday, November 6, 2012 12:53 AM
Subject: [NavList] Re: historical star coordinates
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Hello Peter,
Would you mind giving more details about your starting data ?
From: Peter Hakel
Date: 2012 Nov 6, 05:45 -0800
Hello Kermit,
It was UT, and DeltaT came out: 195667.68 seconds from the "Before the year -500" fit at:
http://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html
Now this source does place the early limit at year -1999, so I did this calculation only as a curiosity, since it involves such a far-out extrapolation into prehistory. I did not dig deeper than that.
It was UT, and DeltaT came out: 195667.68 seconds from the "Before the year -500" fit at:
http://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html
Now this source does place the early limit at year -1999, so I did this calculation only as a curiosity, since it involves such a far-out extrapolation into prehistory. I did not dig deeper than that.
Cheers,
Peter Hakel
From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
To: NavList@fer3.com
Sent: Tuesday, November 6, 2012 12:53 AM
Subject: [NavList] Re: historical star coordinates
RE : [NavList] Re: historical star coordinates
From: Peter Hakel
Date: 23 Oct 2012 22:21
From: Peter Hakel
Date: 23 Oct 2012 22:21
Selected comparisons for the year -6000 between Sky View Cafe and Navigation Spreadsheets. Declination is in columns D-F (and X), right ascension (in degrees) is in column W (for stars) or cell B162 (for planets):
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From Mauritius Island on Nov 06th, 2012
Hello Peter,
Would you mind giving more details about your starting data ?
Did you compute your data for Jan 01, -6000 at 00:00:00 TDT or 00:00:00 UT ? And if you used UT, which TT-UT value did you use ?
An accurate time depiction might not be crucial for stars RA and DEC, however it certainly is for planets
RA and DEC.
Thank you for your Kind Attention and Reply, and
Best Regards
Kermit
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