Changeset 41748 for trunk/Ohana/src/opihi/cmd.astro/astrom_ops.c

Timestamp:

Jul 30, 2021, 3:01:24 PM (5 years ago)

Author:

eugene

Message:

add z component option to parallax factor

File:

• trunk/Ohana/src/opihi/cmd.astro/astrom_ops.c (modified) (1 diff)

trunk/Ohana/src/opihi/cmd.astro/astrom_ops.c

@@ -41 +41 @@
 }
 
+/* given RA, DEC, Time, calculate the parallax factor */
+// RA,DEC are decimal degrees
+// Time is MJD
+int ParFactor_3d (double *pR, double *pD, double *pZ, double RA, double DEC, double Time) {
+
+  double lambda, beta, epsilon, Radius;
+
+  // Time must be mjd
+  sun_ecliptic (Time, &lambda, &beta, &epsilon, &Radius);
+
+  double lambda_rad = lambda*RAD_DEG;
+  double epsilon_rad = epsilon*RAD_DEG;
+  double RA_rad = RA*RAD_DEG;
+  double DEC_rad = DEC*RAD_DEG;
+
+  double x = Radius*cos(lambda_rad);
+  double y = Radius*cos(epsilon_rad)*sin(lambda_rad);
+  double z = Radius*sin(epsilon_rad)*sin(lambda_rad);
+
+  *pR = +(y*cos(RA_rad) - x*sin(RA_rad));
+  *pD = -(y*sin(RA_rad) + x*cos(RA_rad))*sin(DEC_rad) + z*cos(DEC_rad);
+  *pZ = -(y*sin(RA_rad) + x*cos(RA_rad))*cos(DEC_rad) + z*sin(DEC_rad);
+
+  return TRUE;
+}
+
 // allocate arrays but not the container
 int PlxFitDataAlloc (PlxFitData *data, int N) {