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    Re: Regulus Occultation, unexpected results
    From: Antoine Couëtte
    Date: 2017 Sep 30, 22:32 -0700

    RE : SeanC-sep-2017-g40234

    Hello Sean,

    You wrote " In case you weren't already aware, anyone can register with the IERS here and select various bulletins to receive via email. ".

    I had totally forgotten that we can register with the IERS. Thank you very much. Very nice to know since I can immediately enter/modify any deltaT value in my Programs at fingertip.

    For interested readers, just a reminder about why we can safely use the deltaT polynomial series for Classical Celestial Navigation ( https://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html ) vs.IERS data, although these deltaT polynomials are much less accurate than the IERS bulletins data :

    A 6" to 9" accuracy on celestial bodies apparent coordinates is required to adequately process the very best sextant observations (+/- 6" to 9") without degrading them in any manner. The errors resulting from the use of these deltaT polynomial series have remained until now 100% compatible with the objective of being able to generate accurate Ephemerides always equal or better than any and all apparent celestial coordinates obtained from using/interpolating Nautical Almanac(s) printed data (+/- 6" to 9" again). These deltaT polynomials also permit quite meaningful historical research through enabling to compute Ephemerides [significantly] better than the ones published a few centuries ago.

    In conclusion if they are not top notch for our current epoch by almost any standard, these deltaT Polynomial Series are self-contained (no need to hook up onto the internet), they cover an extremely long period (over 2 millennia), and they are sufficiently accurate for Celnav. They do fulfill any and all foreseeable requirements for Classical Celestial Navigation : nowadays, as well as for over many centuries in the past and hopefully for extended periods into future.

    Thanks again Sean for your nice and useful information about easy and automatic access to the IERS Bulletins.


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