1 /* 2 * - - - - - - - - - - - 3 * g a l _ t t 2 m t c 4 * - - - - - - - - - - - 5 * 6 * This routine is part of the General Astrodynamics Library 7 * 8 * Description: 9 * 10 * This routine converts a TT jd date to a Mars Coordinated 11 * Time (MTC) date. Mars Coordinated Time is the Mean Solar 12 * Time on the Mars prime meridian. 13 * 14 * Status: 15 * 16 * support routine. 17 * 18 * Given: 19 * 20 * tt1 d TT date part 1 ( see Note 1 ) 21 * tt2 d TT date part 2 ( see Note 1 ) 22 * 23 * Returned: 24 * 25 * *mtc1 d MTC date part 1 ( see Note 2 ) 26 * *mtc2 d MTC date part 2 ( see Note 2 ) 27 * 28 * Notes: 29 * 30 * 1) The Julian Date is apportioned in any convenient way between 31 * the arguments tai1 and tai2. For example, JD=2450123.7 could 32 * be expressed in any of these ways, among others: 33 * 34 * tt1 tt2 35 * 36 * 2450123.7 0.0 (JD method) 37 * 2451545.0 -1421.3 (J2000 method) 38 * 2400000.5 50123.2 (MJD method) 39 * 2450123.5 0.2 (date & time method) 40 * 41 * 2) mtc1 contains the sol number, and mtc2 the fractional part of the 42 * sol. A Mars "day" is called a "sol". 43 * 44 * 3) As defined, consistent with the terrestrial convention for Mean 45 * Solar Time, JD 2451549.5 (2000 January 6 00:00:00) corresponds to 46 * a near coincidence of the terrestrial Greenwich mean solar 47 * midnight and the Martian mean solar (prime meridian) midnight. The 48 * addition of the integer number 44796 assures a positive result 49 * for any date since JD 2405522 (1873 December 29.5). 50 * 51 * References: 52 * 53 * A post-Pathfinder evaluation of areocentric solar coordinates with 54 * improved timing recipes for Mars seasonal/diurnal climate studies 55 * by Michael Allison, Megan McEwen, 56 * Planetary and Space Science 48 (2000) 215-235 57 * 58 * Mars24 URL: http://www.giss.nasa.gov/tools/mars24/help/algorithm.html 59 * The referenced URL contains corrections to the referenced article. 60 * 61 * This revision: 62 * 63 * 2009 January 5 64 * 65 * Copyright (C) 2009 Paul C. L. Willmott. See notes at end. 66 * 67 *----------------------------------------------------------------------- 68 */ 69 70 #ifndef _GAL_TT2MTC_H_ 71 #define _GAL_TT2MTC_H_ 1 72 73 #undef __BEGIN_DECLS 74 #undef __END_DECLS 75 #ifdef __cplusplus 76 #define __BEGIN_DECLS extern "C" { 77 #define __END_DECLS } 78 #else 79 #define __BEGIN_DECLS /* empty */ 80 #define __END_DECLS /* empty */ 81 #endif 82 83 __BEGIN_DECLS 84 85 void 86 gal_tt2mtc 87 ( 88 double tt1, 89 double tt2, 90 double *mtc1, 91 double *mtc2 92 ) ; 93 94 __END_DECLS 95 96 #endif /* !_GAL_TT2MTC_H_ */ 97 98 /* 99 * gal - General Astrodynamics Library 100 * Copyright (C) 2009 Paul C. L. Willmott 101 * 102 * This program is free software; you can redistribute it and/or modify 103 * it under the terms of the GNU General Public License as published by 104 * the Free Software Foundation; either version 2 of the License, or 105 * (at your option) any later version. 106 * 107 * This program is distributed in the hope that it will be useful, 108 * but WITHOUT ANY WARRANTY; without even the implied warranty of 109 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 110 * GNU General Public License for more details. 111 * 112 * You should have received a copy of the GNU General Public License along 113 * with this program; if not, write to the Free Software Foundation, Inc., 114 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 115 * 116 * Contact: 117 * 118 * Paul Willmott 119 * vp9mu@amsat.org 120 */ 121