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diff --git a/math/slalib/doc/refco.hlp b/math/slalib/doc/refco.hlp new file mode 100644 index 00000000..98be6d4c --- /dev/null +++ b/math/slalib/doc/refco.hlp @@ -0,0 +1,54 @@ +.help refco Jun99 "Slalib Package" +.nf + + SUBROUTINE slRFCO (HM, TDK, PMB, RH, WL, PHI, TLR, EPS, + : REFA, REFB) + + - - - - - - + R F C O + - - - - - - + + 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. + + Given: + HM d height of the observer above sea level (metre) + TDK d ambient temperature at the observer (deg K) + PMB d pressure at the observer (millibar) + RH d relative humidity at the observer (range 0-1) + WL d effective wavelength of the source (micrometre) + PHI d latitude of the observer (radian, astronomical) + TLR d temperature lapse rate in the troposphere (degK/metre) + EPS d precision required to terminate iteration (radian) + + Returned: + REFA d tan Z coefficient (radian) + REFB d tan**3 Z coefficient (radian) + + Called: slRFRO + + Notes: + + 1 Typical values for the TLR and EPS arguments might be 0.0065D0 and + 1D-10 respectively. + + 2 The radio refraction is chosen by specifying WL > 100 micrometres. + + 3 The routine is a slower but more accurate alternative to the + slRFCQ routine. The constants it produces give perfect + agreement with slRFRO 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. + + P.T.Wallace Starlink 3 June 1997 + + Copyright (C) 1997 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp |