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authorJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
committerJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
commit40e5a5811c6ffce9b0974e93cdd927cbcf60c157 (patch)
tree4464880c571602d54f6ae114729bf62a89518057 /math/slalib/precl.f
downloadiraf-osx-40e5a5811c6ffce9b0974e93cdd927cbcf60c157.tar.gz
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+ SUBROUTINE slPREL (EP0, EP1, RMATP)
+*+
+* - - - - - -
+* P R E L
+* - - - - - -
+*
+* Form the matrix of precession between two epochs, using the
+* model of Simon et al (1994), which is suitable for long
+* periods of time.
+*
+* (double precision)
+*
+* Given:
+* EP0 dp beginning epoch
+* EP1 dp ending epoch
+*
+* Returned:
+* RMATP dp(3,3) precession matrix
+*
+* Notes:
+*
+* 1) The epochs are TDB Julian epochs.
+*
+* 2) The matrix is in the sense V(EP1) = RMATP * V(EP0)
+*
+* 3) The absolute accuracy of the model is limited by the
+* uncertainty in the general precession, about 0.3 arcsec per
+* 1000 years. The remainder of the formulation provides a
+* precision of 1 mas over the interval from 1000AD to 3000AD,
+* 0.1 arcsec from 1000BC to 5000AD and 1 arcsec from
+* 4000BC to 8000AD.
+*
+* Reference:
+* Simon, J.L. et al., 1994. Astron.Astrophys., 282, 663-683.
+*
+* Called: slDEUL
+*
+* P.T.Wallace Starlink 23 August 1996
+*
+* Copyright (C) 1996 Rutherford Appleton Laboratory
+*
+* License:
+* 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 2 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 (see SLA_CONDITIONS); if not, write to the
+* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+* Boston, MA 02110-1301 USA
+*
+* Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
+*-
+
+ IMPLICIT NONE
+
+ DOUBLE PRECISION EP0,EP1,RMATP(3,3)
+
+* Arc seconds to radians
+ DOUBLE PRECISION AS2R
+ PARAMETER (AS2R=0.484813681109535994D-5)
+
+ DOUBLE PRECISION T0,T,TAS2R,W,ZETA,Z,THETA
+
+
+
+* Interval between basic epoch J2000.0 and beginning epoch (1000JY)
+ T0 = (EP0-2000D0)/1000D0
+
+* Interval over which precession required (1000JY)
+ T = (EP1-EP0)/1000D0
+
+* Euler angles
+ TAS2R = T*AS2R
+ W = 23060.9097D0+
+ : (139.7459D0+
+ : (-0.0038D0+
+ : (-0.5918D0+
+ : (-0.0037D0+
+ : 0.0007D0*T0)*T0)*T0)*T0)*T0
+
+ ZETA = (W+(30.2226D0+
+ : (-0.2523D0+
+ : (-0.3840D0+
+ : (-0.0014D0+
+ : 0.0007D0*T0)*T0)*T0)*T0+
+ : (18.0183D0+
+ : (-0.1326D0+
+ : (0.0006D0+
+ : 0.0005D0*T0)*T0)*T0+
+ : (-0.0583D0+
+ : (-0.0001D0+
+ : 0.0007D0*T0)*T0+
+ : (-0.0285D0+
+ : (-0.0002D0)*T)*T)*T)*T)*T)*TAS2R
+
+ Z = (W+(109.5270D0+
+ : (0.2446D0+
+ : (-1.3913D0+
+ : (-0.0134D0+
+ : 0.0026D0*T0)*T0)*T0)*T0+
+ : (18.2667D0+
+ : (-1.1400D0+
+ : (-0.0173D0+
+ : 0.0044D0*T0)*T0)*T0+
+ : (-0.2821D0+
+ : (-0.0093D0+
+ : 0.0032D0*T0)*T0+
+ : (-0.0301D0+
+ : 0.0006D0*T0
+ : -0.0001D0*T)*T)*T)*T)*T)*TAS2R
+
+ THETA = (20042.0207D0+
+ : (-85.3131D0+
+ : (-0.2111D0+
+ : (0.3642D0+
+ : (0.0008D0+
+ : (-0.0005D0)*T0)*T0)*T0)*T0)*T0+
+ : (-42.6566D0+
+ : (-0.2111D0+
+ : (0.5463D0+
+ : (0.0017D0+
+ : (-0.0012D0)*T0)*T0)*T0)*T0+
+ : (-41.8238D0+
+ : (0.0359D0+
+ : (0.0027D0+
+ : (-0.0001D0)*T0)*T0)*T0+
+ : (-0.0731D0+
+ : (0.0019D0+
+ : 0.0009D0*T0)*T0+
+ : (-0.0127D0+
+ : 0.0011D0*T0+0.0004D0*T)*T)*T)*T)*T)*TAS2R
+
+* Rotation matrix
+ CALL slDEUL('ZYZ',-ZETA,THETA,-Z,RMATP)
+
+ END