SUBROUTINE iau_STARPM ( RA1, DEC1, PMR1, PMD1, PX1, RV1, : EP1A, EP1B, EP2A, EP2B, : RA2, DEC2, PMR2, PMD2, PX2, RV2, J ) *+ * - - - - - - - - - - - * i a u _ S T A R P M * - - - - - - - - - - - * * Star proper motion: update star catalog data for space motion. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * RA1 d right ascension (radians), before * DEC1 d declination (radians), before * PMR1 d RA proper motion (radians/year), before * PMD1 d Dec proper motion (radians/year), before * PX1 d parallax (arcseconds), before * RV1 d radial velocity (km/s, +ve = receding), before * EP1A d "before" epoch, part A (Note 1) * EP1B d "before" epoch, part B (Note 1) * EP2A d "after" epoch, part A (Note 1) * EP2B d "after" epoch, part B (Note 1) * * Returned: * RA2 d right ascension (radians), after * DEC2 d declination (radians), after * PMR2 d RA proper motion (radians/year), after * PMD2 d Dec proper motion (radians/year), after * PX2 d parallax (arcseconds), after * RV2 d radial velocity (km/s, +ve = receding), after * J i status: * -1 = system error (should not occur) * 0 = no warnings or errors * 1 = distance overridden (Note 6) * 2 = excessive velocity (Note 7) * 4 = solution didn't converge (Note 8) * else = binary logical OR of the above warnings * * Notes: * * 1) The starting and ending TDB epochs EP1A+EP1B and EP2A+EP2B are * Julian Dates, apportioned in any convenient way between the two * parts (A and B). For example, JD(TDB)=2450123.7 could be * expressed in any of these ways, among others: * * EPnA EPnB * * 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) In accordance with normal star-catalog conventions, the object's * right ascension and declination are freed from the effects of * secular aberration. The frame, which is aligned to the catalog * equator and equinox, is Lorentzian and centered on the SSB. * * The proper motions are the rate of change of the right ascension * and declination at the catalog epoch and are in radians per TDB * Julian year. * * The parallax and radial velocity are in the same frame. * * 3) Care is needed with units. The star coordinates are in radians * and the proper motions in radians per Julian year, but the * parallax is in arcseconds. * * 4) The RA proper motion is in terms of coordinate angle, not true * angle. If the catalog uses arcseconds for both RA and Dec proper * motions, the RA proper motion will need to be divided by cos(Dec) * before use. * * 5) Straight-line motion at constant speed, in the inertial frame, * is assumed. * * 6) An extremely small (or zero or negative) parallax is interpreted * to mean that the object is on the "celestial sphere", the radius * of which is an arbitrary (large) value (see the iau_STARPV routine * for the value used). When the distance is overridden in this way, * the status, initially zero, has 1 added to it. * * 7) If the space velocity is a significant fraction of c (see the * constant VMAX in the routine iau_STARPV), it is arbitrarily set to * zero. When this action occurs, 2 is added to the status. * * 8) The relativistic adjustment carried out in the iau_STARPV routine * involves an iterative calculation. If the process fails to * converge within a set number of iterations, 4 is added to the * status. * * Called: * iau_STARPV star catalog data to space motion pv-vector * iau_PVU update a pv-vector * iau_PDP scalar product of two p-vectors * iau_PVSTAR space motion pv-vector to star catalog data * * This revision: 2006 November 13 * * Copyright (C) 2008 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION RA1, DEC1, PMR1, PMD1, PX1, RV1, : EP1A, EP1B, EP2A, EP2B, : RA2, DEC2, PMR2, PMD2, PX2, RV2 INTEGER J * Days to seconds DOUBLE PRECISION D2S PARAMETER ( D2S = 86400D0 ) * Speed of light (AU per day) DOUBLE PRECISION C PARAMETER ( C = D2S/499.004782D0 ) DOUBLE PRECISION PV1(3,2), R, TL1, DT, PV(3,2), R2, RDV, V2, : C2MV2, TL2, PV2(3,2) INTEGER J1, J2 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * RA,Dec etc at the "before" epoch to space motion pv-vector. CALL iau_STARPV ( RA1, DEC1, PMR1, PMD1, PX1, RV1, PV1, J1 ) * Light time when observed (days). CALL iau_PM ( PV1, R ) TL1 = R / C * Time interval, "before" to "after" (days). DT = ( EP2A-EP1A ) + ( EP2B-EP1B ) * Move star along track from the "before" observed position to the * "after" geometric position. CALL iau_PVU ( DT+TL1, PV1, PV ) * From this geometric position, deduce the observed light time (days) * at the "after" epoch (with theoretically unneccessary error check). CALL iau_PDP ( PV(1,1), PV(1,1), R2 ) CALL iau_PDP ( PV(1,1), PV(1,2), RDV ) CALL iau_PDP ( PV(1,2), PV(1,2), V2 ) C2MV2 = C*C - V2 IF ( C2MV2 .LE. 0D0 ) THEN J = -1 GO TO 9 END IF TL2 = ( - RDV + SQRT(RDV*RDV + C2MV2*R2) ) / C2MV2 * Move the position along track from the observed place at the * "before" epoch to the observed place at the "after" epoch. CALL iau_PVU ( DT + ( TL1-TL2 ), PV1, PV2 ) * Space motion pv-vector to RA,Dec etc. at the "after" epoch. CALL iau_PVSTAR ( PV2, RA2, DEC2, PMR2, PMD2, PX2, RV2, J2 ) * Return the status. IF ( J2 .NE. 0 ) J1 = -1 J = J1 * Exit. 9 CONTINUE * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2008 * 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