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Diffstat (limited to 'src/slalib/pm.f')
| -rw-r--r-- | src/slalib/pm.f | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/slalib/pm.f b/src/slalib/pm.f new file mode 100644 index 0000000..82a5772 --- /dev/null +++ b/src/slalib/pm.f @@ -0,0 +1,74 @@ + SUBROUTINE sla_PM (R0, D0, PR, PD, PX, RV, EP0, EP1, R1, D1) +*+ +* - - - +* P M +* - - - +* +* Apply corrections for proper motion to a star RA,Dec +* (double precision) +* +* References: +* 1984 Astronomical Almanac, pp B39-B41. +* (also Lederle & Schwan, Astron. Astrophys. 134, +* 1-6, 1984) +* +* Given: +* R0,D0 dp RA,Dec at epoch EP0 (rad) +* PR,PD dp proper motions: RA,Dec changes per year of epoch +* PX dp parallax (arcsec) +* RV dp radial velocity (km/sec, +ve if receding) +* EP0 dp start epoch in years (e.g. Julian epoch) +* EP1 dp end epoch in years (same system as EP0) +* +* Returned: +* R1,D1 dp RA,Dec at epoch EP1 (rad) +* +* Called: +* sla_DCS2C spherical to Cartesian +* sla_DCC2S Cartesian to spherical +* sla_DRANRM normalize angle 0-2Pi +* +* Note: +* The proper motions in RA are dRA/dt rather than +* cos(Dec)*dRA/dt, and are in the same coordinate +* system as R0,D0. +* +* P.T.Wallace Starlink 23 August 1996 +* +* Copyright (C) 1996 Rutherford Appleton Laboratory +*- + + IMPLICIT NONE + + DOUBLE PRECISION R0,D0,PR,PD,PX,RV,EP0,EP1,R1,D1 + +* Km/s to AU/year multiplied by arc seconds to radians + DOUBLE PRECISION VFR + PARAMETER (VFR=0.21094502D0*0.484813681109535994D-5) + + INTEGER I + DOUBLE PRECISION sla_DRANRM + DOUBLE PRECISION W,EM(3),T,P(3) + + + +* Spherical to Cartesian + CALL sla_DCS2C(R0,D0,P) + +* Space motion (radians per year) + W=VFR*RV*PX + EM(1)=-PR*P(2)-PD*COS(R0)*SIN(D0)+W*P(1) + EM(2)= PR*P(1)-PD*SIN(R0)*SIN(D0)+W*P(2) + EM(3)= PD*COS(D0) +W*P(3) + +* Apply the motion + T=EP1-EP0 + DO I=1,3 + P(I)=P(I)+T*EM(I) + END DO + +* Cartesian to spherical + CALL sla_DCC2S(P,R1,D1) + R1=sla_DRANRM(R1) + + END |