palPa
palPa
- HA, Dec to Parallactic Angle
- Description:
- Converts HA, Dec to Parallactic Angle.
- Invocation:
- double palPa( double ha, double dec, double phi );
- Arguments:
-
-
ha = double (Given)
-
Hour angle in radians (Geocentric apparent)
-
dec = double (Given)
-
Declination in radians (Geocentric apparent)
-
phi = double (Given)
-
Observatory latitude in radians (geodetic)
- Returned Value:
-
-
palPa = double
-
Parallactic angle in the range -pi to
pi.
- Notes:
- The parallactic angle at a point in the sky is the position
angle of the vertical, i.e. the angle between the direction to
the pole and to the zenith. In precise applications care must
be taken only to use geocentric apparent HA,Dec and to consider
separately the effects of atmospheric refraction and telescope
mount errors.
- At the pole a zero result is returned.