SUBROUTINE iau_PMSAFE ( RA1, DEC1, PMR1, PMD1, PX1, RV1, : EP1A, EP1B, EP2A, EP2B, : RA2, DEC2, PMR2, PMD2, PX2, RV2, J ) *+ * - - - - - - - - - - - * i a u _ P M S A F E * - - - - - - - - - - - * * Star proper motion: update star catalog data for space motion, with * special handling to handle the zero parallax case. * * 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 overridden to * ensure that the object is at a finite but very large distance, but * not so large that the proper motion is equivalent to a large but * safe speed (about 0.1c using the chosen constant). A warning * status of 1 is added to the status if this action has been taken. * * 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_SEPS angle between two points * iau_STARPM update star catalog data for space motion * * This revision: 2013 June 6 * * SOFA release 2020-07-21 * * Copyright (C) 2020 IAU SOFA 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 * Minimum allowed parallax (arcsec) DOUBLE PRECISION PXMIN PARAMETER ( PXMIN = 5D-7 ) * Factor giving maximum allowed transverse speed of about 1% c DOUBLE PRECISION F PARAMETER ( F = 326D0 ) INTEGER JPX DOUBLE PRECISION PM, PX1A * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Proper motion in one year (radians). CALL iau_SEPS ( RA1, DEC1, RA1+PMR1, DEC1+PMD1, PM ) * Override the parallax to reduce the chances of a warning status. JPX = 0 PX1A = PX1 PM = PM * F IF ( PX1A .LT. PM ) THEN JPX = 1 PX1A = PM END IF IF ( PX1A .LT. PXMIN ) THEN JPX = 1 PX1A = PXMIN END IF * Carry out the transformation using the modified parallax. CALL iau_STARPM ( RA1, DEC1, PMR1, PMD1, PX1A, RV1, : EP1A, EP1B, EP2A, EP2B, : RA2, DEC2, PMR2, PMD2, PX2, RV2, J ) * Revise the status. IF ( MOD(J,2) .EQ. 0 ) J = J + JPX * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2020 * 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. That portion of your * distribution that does not consist of intact and unchanged copies * of SOFA source code files is a "derived work" that must comply * with the following requirements: * * a) Your work shall be marked or carry a statement that it * (i) uses routines and computations derived by you from * software provided by SOFA under license to you; and * (ii) does not itself constitute software provided by and/or * endorsed by SOFA. * * b) The source code of your derived work must contain descriptions * of how the derived work is based upon, contains and/or differs * from the original SOFA software. * * c) The names of all routines in your derived work shall not * include the prefix "iau" or "sofa" or trivial modifications * thereof such as changes of case. * * d) The origin of the SOFA components of your derived work must * not be misrepresented; you must not claim that you wrote the * original software, nor file a patent application for SOFA * software or algorithms embedded in the SOFA software. * * e) These requirements must be reproduced intact in any source * distribution and shall apply to anyone to whom you have * granted a further right to modify the source code of your * derived work. * * Note that, as originally distributed, the SOFA software is * intended to be a definitive implementation of the IAU standards, * and consequently third-party modifications are discouraged. 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The provision of any version of the SOFA 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. * * In any published work or commercial product which uses the SOFA * software directly, acknowledgement (see www.iausofa.org) is * appreciated. * * Correspondence concerning SOFA software should be addressed as * follows: * * By email: sofa@ukho.gov.uk * By post: IAU SOFA Center * HM Nautical Almanac Office * UK Hydrographic Office * Admiralty Way, Taunton * Somerset, TA1 2DN * United Kingdom * *----------------------------------------------------------------------- END