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palPertel.c
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palPertel.c
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/*
*+
* Name:
* palPertel
* Purpose:
* Update elements by applying planetary perturbations
* Language:
* Starlink ANSI C
* Type of Module:
* Library routine
* Invocation:
* void palPertel (int jform, double date0, double date1,
* double epoch0, double orbi0, double anode0,
* double perih0, double aorq0, double e0, double am0,
* double *epoch1, double *orbi1, double *anode1,
* double *perih1, double *aorq1, double *e1, double *am1,
* int *jstat );
* Arguments:
* jform = int (Given)
* Element set actually returned (1-3; Note 6)
* date0 = double (Given)
* Date of osculation (TT MJD) for the given elements.
* date1 = double (Given)
* Date of osculation (TT MJD) for the updated elements.
* epoch0 = double (Given)
* Epoch of elements (TT MJD)
* orbi0 = double (Given)
* inclination (radians)
* anode0 = double (Given)
* longitude of the ascending node (radians)
* perih0 = double (Given)
* longitude or argument of perihelion (radians)
* aorq0 = double (Given)
* mean distance or perihelion distance (AU)
* e0 = double (Given)
* eccentricity
* am0 = double (Given)
* mean anomaly (radians, JFORM=2 only)
* epoch1 = double * (Returned)
* Epoch of elements (TT MJD)
* orbi1 = double * (Returned)
* inclination (radians)
* anode1 = double * (Returned)
* longitude of the ascending node (radians)
* perih1 = double * (Returned)
* longitude or argument of perihelion (radians)
* aorq1 = double * (Returned)
* mean distance or perihelion distance (AU)
* e1 = double * (Returned)
* eccentricity
* am1 = double * (Returned)
* mean anomaly (radians, JFORM=2 only)
* jstat = int * (Returned)
* status:
* - +102 = warning, distant epoch
* - +101 = warning, large timespan ( > 100 years)
* - +1 to +10 = coincident with planet (Note 6)
* - 0 = OK
* - -1 = illegal JFORM
* - -2 = illegal E0
* - -3 = illegal AORQ0
* - -4 = internal error
* - -5 = numerical error
* Description:
* Update the osculating orbital elements of an asteroid or comet by
* applying planetary perturbations.
* Authors:
* PTW: Pat Wallace (STFC)
* TIMJ: Tim Jenness (JAC, Hawaii)
* {enter_new_authors_here}
* Notes:
* - Two different element-format options are available:
*
* Option JFORM=2, suitable for minor planets:
*
* EPOCH = epoch of elements (TT MJD)
* ORBI = inclination i (radians)
* ANODE = longitude of the ascending node, big omega (radians)
* PERIH = argument of perihelion, little omega (radians)
* AORQ = mean distance, a (AU)
* E = eccentricity, e
* AM = mean anomaly M (radians)
*
* Option JFORM=3, suitable for comets:
*
* EPOCH = epoch of perihelion (TT MJD)
* ORBI = inclination i (radians)
* ANODE = longitude of the ascending node, big omega (radians)
* PERIH = argument of perihelion, little omega (radians)
* AORQ = perihelion distance, q (AU)
* E = eccentricity, e
*
* - DATE0, DATE1, EPOCH0 and EPOCH1 are all instants of time in
* the TT timescale (formerly Ephemeris Time, ET), expressed
* as Modified Julian Dates (JD-2400000.5).
*
* DATE0 is the instant at which the given (i.e. unperturbed)
* osculating elements are correct.
*
* DATE1 is the specified instant at which the updated osculating
* elements are correct.
*
* EPOCH0 and EPOCH1 will be the same as DATE0 and DATE1
* (respectively) for the JFORM=2 case, normally used for minor
* planets. For the JFORM=3 case, the two epochs will refer to
* perihelion passage and so will not, in general, be the same as
* DATE0 and/or DATE1 though they may be similar to one another.
* - The elements are with respect to the J2000 ecliptic and equinox.
* - Unused elements (AM0 and AM1 for JFORM=3) are not accessed.
* - See the palPertue routine for details of the algorithm used.
* - This routine is not intended to be used for major planets, which
* is why JFORM=1 is not available and why there is no opportunity
* to specify either the longitude of perihelion or the daily
* motion. However, if JFORM=2 elements are somehow obtained for a
* major planet and supplied to the routine, sensible results will,
* in fact, be produced. This happens because the palPertue routine
* that is called to perform the calculations checks the separation
* between the body and each of the planets and interprets a
* suspiciously small value (0.001 AU) as an attempt to apply it to
* the planet concerned. If this condition is detected, the
* contribution from that planet is ignored, and the status is set to
* the planet number (1-10 = Mercury, Venus, EMB, Mars, Jupiter,
* Saturn, Uranus, Neptune, Earth, Moon) as a warning.
*
* See Also:
* - Sterne, Theodore E., "An Introduction to Celestial Mechanics",
* Interscience Publishers Inc., 1960. Section 6.7, p199.
* History:
* 2012-03-12 (TIMJ):
* Initial version direct conversion of SLA/F.
* Adapted with permission from the Fortran SLALIB library.
* {enter_further_changes_here}
* Copyright:
* Copyright (C) 2004 Patrick T. Wallace
* Copyright (C) 2012 Science and Technology Facilities Council.
* All Rights Reserved.
* Licence:
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
* Bugs:
* {note_any_bugs_here}
*-
*/
#include "pal.h"
void palPertel (int jform, double date0, double date1,
double epoch0, double orbi0, double anode0,
double perih0, double aorq0, double e0, double am0,
double *epoch1, double *orbi1, double *anode1,
double *perih1, double *aorq1, double *e1, double *am1,
int *jstat ) {
double u[13], dm;
int j, jf;
/* Check that the elements are either minor-planet or comet format. */
if (jform < 2 || jform > 3) {
*jstat = -1;
return;
} else {
/* Provisionally set the status to OK. */
*jstat = 0;
}
/* Transform the elements from conventional to universal form. */
palEl2ue(date0,jform,epoch0,orbi0,anode0,perih0,
aorq0,e0,am0,0.0,u,&j);
if (j != 0) {
*jstat = j;
return;
}
/* Update the universal elements. */
palPertue(date1,u,&j);
if (j > 0) {
*jstat = j;
} else if (j < 0) {
*jstat = -5;
return;
}
/* Transform from universal to conventional elements. */
palUe2el(u, jform, &jf, epoch1, orbi1, anode1, perih1,
aorq1, e1, am1, &dm, &j);
if (jf != jform || j != 0) *jstat = -5;
}