void eraApcs	(	double	date1,
		double	date2,
		double	pv[2][3],
		double	ebpv[2][3],
		double	ehp[3],
		eraASTROM *	astrom
	)

Definition at line 3 of file apcs.c.

References eraASTROM::bm1, eraASTROM::bpn, eraASTROM::eb, eraASTROM::eh, eraASTROM::em, eraCp(), eraIr(), eraPn(), ERFA_AULT, ERFA_DAU, ERFA_DAYSEC, ERFA_DJ00, ERFA_DJY, i, eraASTROM::pmt, and eraASTROM::v.

Referenced by eraApcg(), eraApco(), eraApcs13(), and t_apcs().

{
/* au/d to m/s */
   const double AUDMS = ERFA_DAU/ERFA_DAYSEC;

/* Light time for 1 AU (day) */
   const double CR = ERFA_AULT/ERFA_DAYSEC;

   int i;
   double dp, dv, pb[3], vb[3], ph[3], v2, w;

/* Time since reference epoch, years (for proper motion calculation). */
   astrom->pmt = ( (date1 - ERFA_DJ00) + date2 ) / ERFA_DJY;

/* Adjust Earth ephemeris to observer. */
   for (i = 0; i < 3; i++) {
      dp = pv[0][i] / ERFA_DAU;
      dv = pv[1][i] / AUDMS;
      pb[i] = ebpv[0][i] + dp;
      vb[i] = ebpv[1][i] + dv;
      ph[i] = ehp[i] + dp;
   }

/* Barycentric position of observer (au). */
   eraCp(pb, astrom->eb);

/* Heliocentric direction and distance (unit vector and au). */
   eraPn(ph, &astrom->em, astrom->eh);

/* Barycentric vel. in units of c, and reciprocal of Lorenz factor. */
   v2 = 0.0;
   for (i = 0; i < 3; i++) {
      w = vb[i] * CR;
      astrom->v[i] = w;
      v2 += w*w;
   }
   astrom->bm1 = sqrt(1.0 - v2);

/* Reset the NPB matrix. */
   eraIr(astrom->bpn);

/* Finished. */

}

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