palDh2e
palDh2e
- Horizon to equatorial coordinates: Az,El to HA,Dec
- Description:
- Convert horizon to equatorial coordinates.
- Invocation:
- palDh2e( double az, double el, double phi, double
ha, double
dec );
- Arguments:
-
-
az = double (Given)
-
Azimuth (radians)
-
el = double (Given)
-
Elevation (radians)
-
phi = double (Given)
-
Observatory latitude (radians)
-
ha = double
(Returned)
-
Hour angle (radians)
-
dec = double
(Returned)
-
Declination (radians)
- Notes:
- All the arguments are angles in radians.
- The sign convention for azimuth is north zero, east
pi/2.
- HA is returned in the range
/-pi. Declination is returned
in the range
/-pi/2.
- The latitude is (in principle) geodetic. In critical
applications, corrections for polar motion should be applied.
- In some applications it will be important to specify the
correct type of elevation in order to produce the required
type of HA,Dec. In particular, it may be important to
distinguish between the elevation as affected by refraction,
which will yield the "observed" HA,Dec, and the elevation
in vacuo, which will yield the "topocentric" HA,Dec. If the
effects of diurnal aberration can be neglected, the
topocentric HA,Dec may be used as an approximation to the
"apparent" HA,Dec.
- No range checking of arguments is done.
- In applications which involve many such calculations, rather
than calling the present routine it will be more efficient to
use inline code, having previously computed fixed terms such
as sine and cosine of latitude.