SUBROUTINE iau_LTPB ( EPJ, RPB ) *+ * - - - - - - - - - * i a u _ L T P B * - - - - - - - - - * * Long-term precession matrix, including ICRS frame bias. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * EPJ d Julian epoch (TT) * * Returned: * RPB d precession-bias matrix, J2000.0 to date * * Notes: * * 1) The matrix is in the sense * * P_date = RPB x P_ICRS, * * where P_J2000 is a vector in the International Celestial Reference * System, and P_date is the vector with respect to the Celestial * Intermediate Reference System at that date but with nutation * neglected. * * 2) A first order frame bias formulation is used, of sub- * microarcsecond accuracy compared with a full 3D rotation. * * 3) The Vondrak et al. (2011, 2012) 400 millennia precession model * agrees with the IAU 2006 precession at J2000.0 and stays within * 100 microarcseconds during the 20th and 21st centuries. It is * accurate to a few arcseconds throughout the historical period, * worsening to a few tenths of a degree at the end of the * +/- 200,000 year time span. * * Called: * iau_LTP precession matrix, long term * * References: * * Vondrak, J., Capitaine, N. and Wallace, P., 2011, New precession * expressions, valid for long time intervals, Astron.Astrophys. 534, * A22 * * Vondrak, J., Capitaine, N. and Wallace, P., 2012, New precession * expressions, valid for long time intervals (Corrigendum), * Astron.Astrophys. 541, C1 * * This revision: 2015 December 6 * * SOFA release 2017-04-20 * * Copyright (C) 2017 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION EPJ, RPB(3,3) * Arcseconds to radians DOUBLE PRECISION DAS2R PARAMETER ( DAS2R = 4.848136811095359935899141D-6 ) * Frame bias (IERS Conventions 2010, Eqs. 5.21 and 5.33) DOUBLE PRECISION DX, DE, DR PARAMETER ( DX = -0.016617D0 * DAS2R, : DE = -0.0068192D0 * DAS2R, : DR = -0.0146D0 * DAS2R ) INTEGER I DOUBLE PRECISION RP(3,3) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Precession matrix. CALL iau_LTP ( EPJ, RP ) * Apply the bias. DO 1 I=1,3 RPB(I,1) = RP(I,1) - RP(I,2)*DR + RP(I,3)*DX RPB(I,2) = RP(I,1)*DR + RP(I,2) + RP(I,3)*DE RPB(I,3) = - RP(I,1)*DX - RP(I,2)*DE + RP(I,3) 1 CONTINUE * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2017 * Standards Of Fundamental Astronomy Board * of the International Astronomical Union. * * ===================== * SOFA Software License * ===================== * * NOTICE TO USER: * * BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND * CONDITIONS WHICH APPLY TO ITS USE. * * 1. The Software is owned by the IAU SOFA Board ("SOFA"). * * 2. Permission is granted to anyone to use the SOFA software for any * purpose, including commercial applications, free of charge and * without payment of royalties, subject to the conditions and * restrictions listed below. * * 3. You (the user) may copy and distribute SOFA source code to others, * and use and adapt its code and algorithms in your own software, * on a world-wide, royalty-free basis. 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