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Diffstat (limited to 'src/libcf/helio_vel.c')
| -rw-r--r-- | src/libcf/helio_vel.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/src/libcf/helio_vel.c b/src/libcf/helio_vel.c new file mode 100644 index 0000000..bc069b6 --- /dev/null +++ b/src/libcf/helio_vel.c @@ -0,0 +1,82 @@ +/***************************************************************************** + * Johns Hopkins University + * Center For Astrophysical Sciences + * FUSE + ***************************************************************************** + * + * Synopsis: double helio_vel(double mjdate, double ra, double dec) + * + * Description: Computes the Earth's orbital velocity in the direction + * of ra,dec to convert to heliocentric velocity. + * + * Arguments: double mjdate Mod. Julian date of observation + * double ra (deg) J2000.0 right ascension + * double dec (deg) J2000.0 declination + * + * Returns: double (km/s) velocity in direction of source + * + * Calls: slaEvp evp.f + * slaDcs2c dcs2c.f + * slaDvdv dvdv.f + * + * History: 03/05/98 E. Murphy Begin work. + * 03/05/98 E. Murphy Initial version working + * 05/31/00 peb Implemented cfortran.h calls for slalib + * functions. + * 06/15/01 V. Dixon Correct sign of return value to agree + * with astronomical convention. + * 12/18/03 bjg Change calfusettag.h to calfuse.h + * + * References: This routine makes use of the Starlink set of astronomical + * subroutines (SLALIB). More information can be found at + * http://star-www.rl.ac.uk. + ****************************************************************************/ + +#include <stdio.h> + +#ifdef CFORTRAN +#include "cfortran.h" + +PROTOCCALLSFSUB3(SLA_DCS2C, sla_dcs2c, DOUBLE, DOUBLE, DOUBLEV) +#define slaDcs2c(A, B, V) \ + CCALLSFSUB3(SLA_DCS2C, sla_dcs2c, DOUBLE, DOUBLE, DOUBLEV, A, B, V) + +PROTOCCALLSFFUN2(DOUBLE, SLA_DVDV, sla_dvdv, DOUBLEV, DOUBLEV) +#define slaDvdv(VA, VB) \ + CCALLSFFUN2(SLA_DVDV, sla_dvdv, DOUBLEV, DOUBLEV, VA, VB) + +PROTOCCALLSFSUB6(SLA_EVP, sla_evp, DOUBLE, DOUBLE, DOUBLEV, DOUBLEV, \ + DOUBLEV, DOUBLEV) +#define slaEvp(DATE, DEQX, DVB, DPB, DVH, DPH) \ + CCALLSFSUB6(SLA_EVP, sla_evp, DOUBLE, DOUBLE, DOUBLEV, DOUBLEV, \ + DOUBLEV, DOUBLEV, DATE, DEQX, DVB, DPB, DVH, DPH) +#else +#include "slalib.h" +#include "slamac.h" +#endif + +#include "calfuse.h" + +double helio_vel(double mjdate, double ra, double dec) +{ + /* Define variables. */ + double dvb[3], dpb[3], dvh[3], dph[3], vect[3]; + /* + * Evp returns four 3-vectors containing the barycentric velocity and + * position (dvb,dpb) and the heliocentric velocity and position + * (dvh,dph) of the Earth on the date mjdate. It requires a modified + * Julian date as input. Output has units of AU for positions and + * AU/s for velocities. + */ + slaEvp(mjdate, 2000.0, dvb, dpb, dvh, dph); + + /* Convert the J2000.0 RA and DEC into a 3-vector position */ + + slaDcs2c(RADIAN*ra, RADIAN*dec, vect); + /* + * Compute the dot product of the RA DEC position vector and the + * heliocentric velocity vector. Mutliply by km/AU to get velocity + * in km/s. + */ + return slaDvdv(vect, dvh)*149.5978707E6; +} |