1 /* 2 * - - - - - - - - - 3 * g a l _ e e 0 0 4 * - - - - - - - - - 5 * 6 * This routine is part of the General Astrodynamics Library 7 * 8 * Description: 9 * 10 * The equation of the equinoxes, compatible with IAU 2000 resolutions, 11 * given the nutation in longitude and the mean obliquity. 12 * 13 * This routine is an independent translation of a FORTRAN routine 14 * that is part of IAU's SOFA software collection. 15 * 16 * Status: 17 * 18 * canonical model. 19 * 20 * Given: 21 * 22 * date1,date2 d TT as a 2-part Julian Date (Note 1) 23 * epsa d mean obliquity (Note 2) 24 * dpsi d nutation in longitude (Note 3) 25 * 26 * Returned: 27 * 28 * gal_ee00 d equation of the equinoxes (Note 4) 29 * 30 * Notes: 31 * 32 * 1) The TT date date1+date2 is a Julian Date, apportioned in any 33 * convenient way between the two arguments. For example, 34 * JD(TT)=2450123.7 could be expressed in any of these ways, 35 * among others: 36 * 37 * date1 date2 38 * 39 * 2450123.7 0.0 (JD method) 40 * 2451545.0 -1421.3 (J2000 method) 41 * 2400000.5 50123.2 (MJD method) 42 * 2450123.5 0.2 (date & time method) 43 * 44 * The JD method is the most natural and convenient to use in 45 * cases where the loss of several decimal digits of resolution 46 * is acceptable. The J2000 method is best matched to the way 47 * the argument is handled internally and will deliver the 48 * optimum resolution. The MJD method and the date & time methods 49 * are both good compromises between resolution and convenience. 50 * 51 * 2) The obliquity, in radians, is mean of date. 52 * 53 * 3) The result, which is in radians, operates in the following sense: 54 * 55 * Greenwich apparent ST = GMST + equation of the equinoxes 56 * 57 * 4) The result is compatible with the IAU 2000 resolutions. For 58 * further details, see IERS Conventions 2003 and Capitaine et al. 59 * (2002). 60 * 61 * Called: 62 * 63 * gal_eect00 equation of the equinoxes complementary terms 64 * 65 * References: 66 * 67 * Capitaine, N., Wallace, P.T. and McCarthy, D.D., "Expressions to 68 * implement the IAU 2000 definition of UT1", Astronomy & 69 * Astrophysics, 406, 1135-1149 (2003) 70 * 71 * McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), 72 * IERS Technical Note No. 32, BKG (2004) 73 * 74 * This revision: 75 * 76 * 2006 November 13 ( c version 2008 January 18 ) 77 * 78 * 79 * Copyright (C) 2008 Paul C. L. Willmott. See notes at end. 80 * 81 *----------------------------------------------------------------------- 82 */ 83 84 #ifndef _GAL_EE00_H_ 85 #define _GAL_EE00_H_ 1 86 87 #undef __BEGIN_DECLS 88 #undef __END_DECLS 89 #ifdef __cplusplus 90 #define __BEGIN_DECLS extern "C" { 91 #define __END_DECLS } 92 #else 93 #define __BEGIN_DECLS /* empty */ 94 #define __END_DECLS /* empty */ 95 #endif 96 97 __BEGIN_DECLS 98 99 double 100 gal_ee00 101 ( 102 double date1, 103 double date2, 104 double epsa, 105 double dpsi 106 ) ; 107 108 __END_DECLS 109 110 #endif /* !_GAL_EE00_H_ */ 111 112 /* 113 * gal - General Astrodynamics Library 114 * Copyright (C) 2008 Paul C. L. Willmott 115 * 116 * This program is free software; you can redistribute it and/or modify 117 * it under the terms of the GNU General Public License as published by 118 * the Free Software Foundation; either version 2 of the License, or 119 * (at your option) any later version. 120 * 121 * This program is distributed in the hope that it will be useful, 122 * but WITHOUT ANY WARRANTY; without even the implied warranty of 123 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 124 * GNU General Public License for more details. 125 * 126 * You should have received a copy of the GNU General Public License along 127 * with this program; if not, write to the Free Software Foundation, Inc., 128 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 129 * 130 * Contact: 131 * 132 * Paul Willmott 133 * vp9mu@amsat.org 134 */ 135