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RE  : http://fer3.com/arc/m2.aspx/Where-world-am-I-RonJones-nov-2017-g40582

and : http://fer3.com/arc/m2.aspx/Where-world-am-I-Dekker-nov-2017-g40585

Dear Herman and Dear Ron,

Thanks to both of you for your interesting contributions.

To you Herman since from reprocessing the Mirfak - Canopus - Peacock topocentric heights subsequently "reverse engineered" from Ron’s published geocentric heights you got a very good end result this time, extremely close from Ron’s published position. So … the TI89 StarPilot Software automatically performs refraction corrections. This is a very good point.

And to you Ron for the info on your https://www.uspsd16.org website and for its very interesting CelNav related documentation. I wish I had such wonderful tools at my hands and fingertips - as this one of yours, or Andrés' or Peter's or Paul's - when learning CelNav by the end of the last Millenium. Warmest Congratulations then ! I can also see that all your Stars apparent coordinates are currently quite accurate, to much better than one arc-second. Wow ! :-)

Once again Jean Meeus' ASTRONOMICAL ALGORITHMS book has proven a gold mine to whoever wishes to program an extensive CelNav package including Ephemeris.

One of the greatest benefits of spreadsheets / calculators has been to make linear regressions affordable and easy or - even more expeditiously - to simply retain the observations average values which mathematically belong to such linear regressions, which again is quite visible on Ron's plots. Sights averaging brings a definite accuracy improvement.

Well done again !

Have a great day !

Kermit