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SUBROUTINE slNUT (DATE, RMATN)
*+
* - - - -
* N U T
* - - - -
*
* Form the matrix of nutation for a given date - Shirai & Fukushima
* 2001 theory (double precision)
*
* Reference:
* Shirai, T. & Fukushima, T., Astron.J. 121, 3270-3283 (2001).
*
* Given:
* DATE d TDB (loosely ET) as Modified Julian Date
* (=JD-2400000.5)
* Returned:
* RMATN d(3,3) nutation matrix
*
* Notes:
*
* 1 The matrix is in the sense v(true) = rmatn * v(mean) .
* where v(true) is the star vector relative to the true equator and
* equinox of date and v(mean) is the star vector relative to the
* mean equator and equinox of date.
*
* 2 The matrix represents forced nutation (but not free core
* nutation) plus corrections to the IAU~1976 precession model.
*
* 3 Earth attitude predictions made by combining the present nutation
* matrix with IAU~1976 precession are accurate to 1~mas (with
* respect to the ICRS) for a few decades around 2000.
*
* 4 The distinction between the required TDB and TT is always
* negligible. Moreover, for all but the most critical applications
* UTC is adequate.
*
* Called: slNUTC, slDEUL
*
* Last revision: 1 December 2005
*
* Copyright P.T.Wallace. All rights reserved.
*
* 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 DATE,RMATN(3,3)
DOUBLE PRECISION DPSI,DEPS,EPS0
* Nutation components and mean obliquity
CALL slNUTC(DATE,DPSI,DEPS,EPS0)
* Rotation matrix
CALL slDEUL('XZX',EPS0,-DPSI,-(EPS0+DEPS),RMATN)
END
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