Description:
Determine the constants A and B in the atmospheric refraction model dZ = A tan Z
+ B
tan
∗∗3
Z.
Z is the " observed" zenith distance (i.e. affected by refraction) and dZ is what to add to Z to give the "
topocentric" (i.e. in vacuo) zenith distance.
Invocation
void palRefco ( double hm, double tdk,
double pmb, double rh, double wl, double phi, double tlr, double eps, double
∗refa,
double ∗refb
);
Arguments
hm = double (Given)
Height of the observer above sea level (metre)
tdk = double
(Given)
Ambient temperature at the observer (K)
pmb = double (Given)
Pressure at the observer
(millibar)
rh = double (Given)
Relative humidity at the observer (range 0-1)
wl = double (Given)
Effective wavelength of the source (micrometre)
phi = double (Given)
Latitude of the observer
(radian, astronomical)
tlr = double (Given)
Temperature lapse rate in the troposphere (K/metre)
eps = double (Given)
Precision required to terminate iteration (radian)
refa = double
∗ (Returned)
tan Z coefficient
(radian)
refb = double ∗ (Returned)
tan∗∗3
Z coefficient (radian)
Notes:
-
Typical values for the TLR and EPS arguments might be 0.0065 and 1E-10 respectively.
-
The radio refraction is chosen by specifying WL
> 100
micrometres.
-
The routine is a slower but more accurate alternative to the palRefcoq routine. The
constants it produces give perfect agreement with palRefro at zenith distances
arctan(1) (45 deg) and arctan(4) (about 76 deg). It achieves 0.5 arcsec accuracy for ZD
< 80 deg, 0.01 arcsec accuracy
for ZD < 60 deg, and 0.001
arcsec accuracy for ZD <
45 deg.
Copyright © 2012 Science and Technology Facilities Council.
Copyright © 2014 Cornell University.
Copyright © 2015 Tim Jenness