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Sun Polynomials again
From: Gordon Talge
Date: 2002 Oct 29, 22:42 -0800
From: Gordon Talge
Date: 2002 Oct 29, 22:42 -0800
This is another version of a polynomial approximation of the Sun for the month of November. -- Gordon -- ,,, (. .) +-------------------------ooO-(_)-Ooo------------------------+ | Gordon Talge WB6YKK e-mail: gtalge@pe.net | | Department of Mathematics http://www.lbusd.k12.ca.us | | Wilson High School Long Beach, CA | | (o- Debian / GNU / Linux | | //\ The Choice of the GNU Generation | | v_/_ .oooO | | - E Aho Laula - ( ) Oooo. - Wider is Better - | +-------------------------\ (---( )-------------------------+ \_) ) / (_/ This is a polynomial series like the British "Compact data for navigation Al astronomy". I have not seen the "Official" polynomials for 2002, so I don't know how compare, but they are probably not exactly the same. The time argument is a little different from the USNAO "Almanac for Computers". For these polynomials it is: x = ( d + GMT/24 ) / 32 Example: GHA, dec and SD required for the Sun on Nov 11, 2002 at 11h 11m 11s. So, d = 11, GMT = 11.18639h and x = 0.35832 Evaluating the 4th degree polynomial we get GHA-GMT = 12.26632h Now add the GMT used so GHA in hrs = 12.26632+11.18639 = 23.45270h Remove multiples of 24h. In this case we don't have to. GHA = 23.45270 x 15 = 351.79056 or 351 degs 47.4' For Dec evaluating the polynomial we get -17.43920 or S 17 degs 26.4' For SD we get 0.2696 x 60 = 16.2' The Nautical Almanac gives: GHA 351 degs 47.4' Dec S 17 degs 26.3' and SD 16.2'. The British polynomials are 5 decimals for GHA-GMT and 4 for Dec, and 4 for S.D., but only 2 terms for S.D. There is also a statement that "Corrections have been incorporated in the data for Venus and Mars to allow for their phase, so that the position obtained from the polynomial coefficients...is for the observed centre-of-light." Not sure what this correction is and how to apply it yet for the planets. Dates: Nov. 1 - Nov. 32 Aries Sun Sun Sun GHA GHA-GMT Dec. S.D. Term h h ° ° 0 2.60818 12.27251 -13.9768 0.2688 1 2.10270 0.02402 -10.4206 0.0022 2 0.00003 -0.11192 1.8732 0.0003 3 0.00002 -0.01273 0.6966 -0.0008 4 -0.00003 0.00866 -0.0658 0.0003