| 1 | /*
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| 2 | *+
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| 3 | * Name:
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| 4 | * palAoppat
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| 5 |
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| 6 | * Purpose:
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| 7 | * Recompute sidereal time to support apparent to observed place
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| 8 |
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| 9 | * Language:
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| 10 | * Starlink ANSI C
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| 11 |
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| 12 | * Type of Module:
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| 13 | * Library routine
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| 14 |
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| 15 | * Invocation:
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| 16 | * void palAoppat( double date, double aoprms[14] );
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| 17 |
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| 18 | * Arguments:
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| 19 | * date = double (Given)
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| 20 | * UTC date/time (modified Julian Date, JD-2400000.5)
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| 21 | * (see palAoppa description for comments on leap seconds)
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| 22 | * aoprms = double[14] (Given & Returned)
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| 23 | * Star-independent apparent-to-observed parameters. Updated
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| 24 | * by this routine. Requires element 12 to be the longitude +
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| 25 | * eqn of equinoxes + sidereal DUT and fills in element 13
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| 26 | * with the local apparent sidereal time (in radians).
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| 27 |
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| 28 | * Description:
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| 29 | * This routine recomputes the sidereal time in the apparent to
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| 30 | * observed place star-independent parameter block.
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| 31 |
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| 32 | * Authors:
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| 33 | * TIMJ: Tim Jenness (JAC, Hawaii)
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| 34 | * PTW: Patrick T. Wallace
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| 35 | * {enter_new_authors_here}
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| 36 |
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| 37 | * Notes:
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| 38 | * - See palAoppa for more information.
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| 39 | * - The star-independent parameters are not treated as an opaque
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| 40 | * struct in order to retain compatibility with SLA.
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| 41 |
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| 42 | * History:
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| 43 | * 2012-08-24 (TIMJ):
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| 44 | * Initial version, ported from Fortran SLA source.
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| 45 | * Adapted with permission from the Fortran SLALIB library.
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| 46 | * {enter_further_changes_here}
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| 47 |
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| 48 | * Copyright:
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| 49 | * Copyright (C) 1995 Rutherford Appleton Laboratory
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| 50 | * Copyright (C) 2012 Science and Technology Facilities Council.
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| 51 | * All Rights Reserved.
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| 52 |
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| 53 | * Licence:
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| 54 | * This program is free software; you can redistribute it and/or
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| 55 | * modify it under the terms of the GNU General Public License as
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| 56 | * published by the Free Software Foundation; either version 3 of
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| 57 | * the License, or (at your option) any later version.
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| 58 | *
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| 59 | * This program is distributed in the hope that it will be
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| 60 | * useful, but WITHOUT ANY WARRANTY; without even the implied
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| 61 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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| 62 | * PURPOSE. See the GNU General Public License for more details.
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| 63 | *
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| 64 | * You should have received a copy of the GNU General Public License
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| 65 | * along with this program; if not, write to the Free Software
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| 66 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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| 67 | * MA 02110-1301, USA.
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| 68 |
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| 69 | * Bugs:
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| 70 | * {note_any_bugs_here}
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| 71 | *-
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| 72 | */
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| 73 |
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| 74 | #include "pal.h"
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| 75 |
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| 76 | static double pal__Gmst( double ut1 );
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| 77 |
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| 78 | void palAoppat( double date, double aoprms[14] ) {
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| 79 | aoprms[13] = pal__Gmst(date) + aoprms[12];
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| 80 | }
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| 81 |
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| 82 | /* Use a private implementation of palGmst for testing that matches
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| 83 | the SLA rather than SOFA/ERFA implementation. This is used for comparing
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| 84 | SLA with PAL refraction code. */
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| 85 |
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| 86 | #include "math.h"
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| 87 | #include "palmac.h"
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| 88 |
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| 89 | static double pal__Gmst( double ut1 ) {
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| 90 |
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| 91 | double tu;
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| 92 | double gmst;
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| 93 |
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| 94 | /* Julian centuries from fundamental epoch J2000 to this UT */
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| 95 | tu=(ut1-51544.5)/36525;
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| 96 |
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| 97 | /* GMST at this UT */
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| 98 | gmst=palDranrm(fmod(ut1,1.0)*PAL__D2PI+
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| 99 | (24110.54841+
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| 100 | (8640184.812866+
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| 101 | (0.093104-6.2e-6*tu)*tu)*tu)*PAL__DS2R);
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| 102 | return gmst;
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| 103 | }
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