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1 files changed, 46 insertions, 0 deletions

diff --git a/src/libcf/space_vel.c b/src/libcf/space_vel.c
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+/*****************************************************************************
+ *              Johns Hopkins University
+ *              Center For Astrophysical Sciences
+ *              FUSE
+ *****************************************************************************
+ *
+ * Synopsis:    double space_vel(double *vel, double ra, double dec)
+ *
+ * Description: Computes the projection of the spacecraft orbital velocity 
+ *		vector onto a unit vector in the direction ra, dec.
+ *
+ * Arguments:   double *vel           (km/s) 3-vector velocity of satellite
+ *              double ra,dec         (deg) position of target
+ *
+ * Returns:     double                (km/s) velocity in direction of target
+ *                    
+ * History:     03/04/98  E. Murphy   Begin work.
+ *              03/04/98  E. Murphy   Initial version working
+ *              07/07/99  E. Murphy   Converted x,y,z and vx,vy,vz to pos,vel
+ *              06/15/01  V. Dixon    Comment out calculation of r, not used.
+ *              12/18/03  bjg         Change calfusettag.h to calfuse.h
+ *		07/21/04  1.4  wvd    Delete defn of r, as it is not used.
+ *		03/04/07  1.5  wvd    Rewrite program to compute dot product
+ *				      of target and velocity vectors.
+ *
+ ****************************************************************************/
+ 
+#include <math.h>
+#include "calfuse.h"
+ 
+double space_vel(double vel[3], double ra, double dec)
+{
+
+    double x, y, z, phi;
+
+    ra  *= RADIAN;
+    dec *= RADIAN;
+
+    z = sin(dec);
+    phi = cos(dec);
+    y = phi * sin(ra);
+    x = phi * cos(ra);
+
+    return x*vel[0] + y*vel[1] + z*vel[2];
+
+}