palAmpqk
palAmpqk
- Convert star RA,Dec from geocentric apparent to mean place
- Description:
- Convert star RA,Dec from geocentric apparent to mean place. The "mean"
coordinate system is in fact close to ICRS. Use of this function
is appropriate when efficiency is important and where many star
positions are all to be transformed for one epoch and equinox. The
star-independent parameters can be obtained by calling the palMappa
function.
- Invocation:
- void palAmpqk ( double ra, double da, double amprms[21],
double
rm, double
dm )
- Arguments:
-
-
ra = double (Given)
-
Apparent RA (radians).
-
da = double (Given)
-
Apparent Dec (radians).
-
amprms = double[21] (Given)
-
Star-independent mean-to-apparent parameters (see palMappa):
(0) time interval for proper motion (Julian years)
(1-3) barycentric position of the Earth (AU)
(4-6) not used
(7) not used
(8-10) abv: barycentric Earth velocity in units of c
(11) sqrt(1-v
v) where v=modulus(abv)
(12-20) precession/nutation (3,3) matrix
-
rm = double (Returned)
-
Mean RA (radians).
-
dm = double (Returned)
-
Mean Dec (radians).