palOap

Observed to apparent place

Description:

Observed to apparent place.

Invocation

void palOap ( const char type, double ob1, double ob2, double date, double dut, double elongm, double phim, double hm, double xp, double yp, double tdk, double pmb, double rh, double wl, double tlr, double rap, double dap );

Arguments

type = const char (Given)
Type of coordinates - R , H or A (see below)
ob1 = double (Given)
Observed Az, HA or RA (radians; Az is N=0;E=90)
ob2 = double (Given)
Observed ZD or Dec (radians)
date = double (Given)
UTC date/time (Modified Julian Date, JD-2400000.5)
dut = double (Given)
delta UT: UT1-UTC (UTC seconds)
elongm = double (Given)
Mean longitude of the observer (radians, east +ve)
phim = double (Given)
Mean geodetic latitude of the observer (radians)
hm = double (Given)
Observer s height above sea level (metres)
xp = double (Given)
Polar motion x-coordinates (radians)
yp = double (Given)
Polar motion y-coordinates (radians)
tdk = double (Given)
Local ambient temperature (K; std=273.15)
pmb = double (Given)
Local atmospheric pressure (mb; std=1013.25)
rh = double (Given)
Local relative humidity (in the range 0.0-1.0)
wl = double (Given)
Effective wavelength (micron, e.g. 0.55)
tlr = double (Given)
Tropospheric laps rate (K/metre, e.g. 0.0065)
rap = double (Given)
Geocentric apparent right ascension
dap = double (Given)
Geocentric apparent declination

Notes:

HM -29.3TSLLOG(P/1013.25).

where TSL is the approximate sea-level air temperature in K (see Astrophysical Quantities, C.W.Allen, 3rd edition, section 52). Similarly, if the pressure P is not known, it can be estimated from the height of the observing station, HM, as follows:

P 1013.25EXP(-HM/(29.3TSL)).

Note, however, that the refraction is nearly proportional to the pressure and that an accurate P value is important for precise work.