SUBROUTINE iau_HFK5Z ( RH, DH, EPOCH1, EPOCH2, R5, D5, DR5, DD5 ) *+ * - - - - - - - - - - * i a u _ H F K 5 Z * - - - - - - - - - - * * Transform a Hipparcos star position into FK5 J2000, assuming * zero Hipparcos proper motion. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * RH d Hipparcos RA (radians) * DH d Hipparcos Dec (radians) * EPOCH1,EPOCH2 d TDB epoch (Note 1) * * Returned (all FK5, equinox J2000, epoch EPOCH1+EPOCH2): * R5 d RA (radians) * D5 d Dec (radians) * DR5 d FK5 RA proper motion (rad/year, Note 4) * DD5 d Dec proper motion (rad/year, Note 4) * * Notes: * * 1) The epoch EPOCH1+EPOCH2 is a Julian Date, apportioned in any * convenient way between the two arguments. For example, * JD(TDB)=2450123.7 could be expressed in any of these ways, * among others: * * EPOCH1 EPOCH2 * * 2450123.7D0 0D0 (JD method) * 2451545D0 -1421.3D0 (J2000 method) * 2400000.5D0 50123.2D0 (MJD method) * 2450123.5D0 0.2D0 (date & time method) * * The JD method is the most natural and convenient to use in * cases where the loss of several decimal digits of resolution * is acceptable. The J2000 method is best matched to the way * the argument is handled internally and will deliver the * optimum resolution. The MJD method and the date & time methods * are both good compromises between resolution and convenience. * * 2) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt. * * 3) The FK5 to Hipparcos transformation is modeled as a pure * rotation and spin; zonal errors in the FK5 catalogue are * not taken into account. * * 4) It was the intention that Hipparcos should be a close * approximation to an inertial frame, so that distant objects * have zero proper motion; such objects have (in general) * non-zero proper motion in FK5, and this routine returns those * fictitious proper motions. * * 5) The position returned by this routine is in the FK5 J2000 * reference frame but at Julian epoch EPOCH1+EPOCH2. * * 6) See also iau_FK52H, iau_H2FK5, iau_FK5ZHZ. * * Called: * iau_S2C spherical to unit vector * iau_FK5HIP FK5 rotation and spin wrt to Hipparcos * iau_RXP product of r-matrix and p-vector * iau_SXP product of scalar and p-vector * iau_RXR r-matrix multiply * iau_TRXP product of transpose of r-matrix and p-vector * iau_PXP vector product of two p-vectors * iau_PV2S pv-vector to spherical * iau_ANP normalize radians to range 0 to 2pi * * Reference: * * M.Feissel & F.Mignard, Astron. Astrophys. 331, L33-L36 (1998). * * This revision: 2001 January 4 * * Copyright (C) 2001 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION RH, DH, EPOCH1, EPOCH2, R5, D5, DR5, DD5 * Reference epoch (J2000), JD DOUBLE PRECISION DJ0 PARAMETER ( DJ0 = 2451545D0 ) * Days per Julian year DOUBLE PRECISION DJY PARAMETER ( DJY = 365.25D0 ) DOUBLE PRECISION T, PH(3), R5H(3,3), S5H(3), SH(3), VST(3), : RST(3,3), R5HT(3,3), PV5E(3,2), VV(3), : W, R, V DOUBLE PRECISION iau_ANP * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Time interval from fundamental epoch J2000.0 to given epoch (JY). T = ( ( EPOCH1-DJ0 ) + EPOCH2 ) / DJY * Hipparcos barycentric position vector (normalized). CALL iau_S2C ( RH, DH, PH ) * FK5 to Hipparcos orientation matrix and spin vector. CALL iau_FK5HIP ( R5H, S5H ) * Rotate the spin into the Hipparcos frame. CALL iau_RXP ( R5H, S5H, SH ) * Accumulated Hipparcos wrt FK5 spin over that interval. CALL iau_SXP ( T, S5H, VST ) * Express the accumulated spin as a rotation matrix. CALL iau_RV2M ( VST, RST ) * Rotation matrix: accumulated spin, then FK5 to Hipparcos. CALL iau_RXR ( R5H, RST, R5HT ) * De-orient & de-spin the Hipparcos position into FK5 J2000. CALL iau_TRXP ( R5HT, PH, PV5E ) * Apply spin to the position giving a space motion. CALL iau_PXP ( SH, PH, VV ) * De-orient & de-spin the Hipparcos space motion into FK5 J2000. CALL iau_TRXP ( R5HT, VV, PV5E(1,2) ) * FK5 position/velocity pv-vector to spherical. CALL iau_PV2S ( PV5E, W, D5, R, DR5, DD5, V ) R5 = iau_ANP ( W ) * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2001 * Standards Of Fundamental Astronomy Review Board * of the International Astronomical Union. * * ===================== * SOFA Software License * ===================== * * NOTICE TO USER: * * BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING TERMS AND CONDITIONS * WHICH APPLY TO ITS USE. * * 1. The Software is owned by the IAU SOFA Review Board ("the Board"). * * 2. The Software is made available free of charge for use by: * * a) private individuals for non-profit research; and * * b) non-profit educational, academic and research institutions. * * 3. Commercial use of the Software is specifically excluded from the * terms and conditions of this license. Commercial use of the * Software is subject to the prior written agreement of the Board on * terms to be agreed. * * 4. The provision of any version of the Software under the terms and * conditions specified herein does not imply that future versions * will also be made available under the same terms and conditions. * * 5. The user may modify the Software for his/her own purposes. The * user may distribute the modified software provided that the Board * is informed and that a copy of the modified software is made * available to the Board on request. All modifications made by the * user shall be clearly identified to show how the modified software * differs from the original Software, and the name(s) of the * affected routine(s) shall be changed. The original SOFA Software * License text must be present. * * 6. In any published work produced by the user and which includes * results achieved by using the Software, the user shall acknowledge * that the Software was used in producing the information contained * in such publication. * * 7. The user may incorporate or embed the Software into other software * products which he/she may then give away free of charge but not * sell provided the user makes due acknowledgement of the use which * he/she has made of the Software in creating such software * products. Any redistribution of the Software in this way shall be * made under the same terms and conditions under which the user * received it from the SOFA Center. * * 8. The user shall not cause the Software to be brought into * disrepute, either by misuse, or use for inappropriate tasks, or by * inappropriate modification. * * 9. The Software is provided to the user "as is" and the Board makes * no warranty as to its use or performance. The Board does not and * cannot warrant the performance or results which the user may * obtain by using the Software. The Board makes no warranties, * express or implied, as to non-infringement of third party rights, * merchantability, or fitness for any particular purpose. In no * event will the Board be liable to the user for any consequential, * incidental, or special damages, including any lost profits or lost * savings, even if a Board representative has been advised of such * damages, or for any claim by any third party. * * Correspondence concerning SOFA software should be addressed as * follows: * * Internet email: sofa@rl.ac.uk * Postal address: IAU SOFA Center * Rutherford Appleton Laboratory * Chilton, Didcot, Oxon OX11 0QX * United Kingdom * * *----------------------------------------------------------------------- END