1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
|
/*****************************************************************************
* 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];
}
|
