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SUBROUTINE sla_PREBN (BEP0, BEP1, RMATP)
*+
* - - - - - -
* P R E B N
* - - - - - -
*
* Generate the matrix of precession between two epochs,
* using the old, pre-IAU1976, Bessel-Newcomb model, using
* Kinoshita's formulation (double precision)
*
* Given:
* BEP0 dp beginning Besselian epoch
* BEP1 dp ending Besselian epoch
*
* Returned:
* RMATP dp(3,3) precession matrix
*
* The matrix is in the sense V(BEP1) = RMATP * V(BEP0)
*
* Reference:
* Kinoshita, H. (1975) 'Formulas for precession', SAO Special
* Report No. 364, Smithsonian Institution Astrophysical
* Observatory, Cambridge, Massachusetts.
*
* Called: sla_DEULER
*
* P.T.Wallace Starlink 23 August 1996
*
* Copyright (C) 1996 Rutherford Appleton Laboratory
*-
IMPLICIT NONE
DOUBLE PRECISION BEP0,BEP1,RMATP(3,3)
* Arc seconds to radians
DOUBLE PRECISION AS2R
PARAMETER (AS2R=0.484813681109535994D-5)
DOUBLE PRECISION BIGT,T,TAS2R,W,ZETA,Z,THETA
* Interval between basic epoch B1850.0 and beginning epoch in TC
BIGT = (BEP0-1850D0)/100D0
* Interval over which precession required, in tropical centuries
T = (BEP1-BEP0)/100D0
* Euler angles
TAS2R = T*AS2R
W = 2303.5548D0+(1.39720D0+0.000059D0*BIGT)*BIGT
ZETA = (W+(0.30242D0-0.000269D0*BIGT+0.017996D0*T)*T)*TAS2R
Z = (W+(1.09478D0+0.000387D0*BIGT+0.018324D0*T)*T)*TAS2R
THETA = (2005.1125D0+(-0.85294D0-0.000365D0*BIGT)*BIGT+
: (-0.42647D0-0.000365D0*BIGT-0.041802D0*T)*T)*TAS2R
* Rotation matrix
CALL sla_DEULER('ZYZ',-ZETA,THETA,-Z,RMATP)
END
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