From 40e5a5811c6ffce9b0974e93cdd927cbcf60c157 Mon Sep 17 00:00:00 2001 From: Joe Hunkeler Date: Tue, 11 Aug 2015 16:51:37 -0400 Subject: Repatch (from linux) of OSX IRAF --- math/slalib/doc/airmas.hlp | 51 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 math/slalib/doc/airmas.hlp (limited to 'math/slalib/doc/airmas.hlp') diff --git a/math/slalib/doc/airmas.hlp b/math/slalib/doc/airmas.hlp new file mode 100644 index 00000000..c347bb50 --- /dev/null +++ b/math/slalib/doc/airmas.hlp @@ -0,0 +1,51 @@ +.help airmas Jun99 "Slalib Package" +.nf + + DOUBLE PRECISION FUNCTION slARMS (ZD) + + - - - - - - - + A R M S + - - - - - - - + + Air mass at given zenith distance (double precision) + + Given: + ZD d Observed zenith distance (radians) + + The result is an estimate of the air mass, in units of that + at the zenith. + + Notes: + + 1) The "observed" zenith distance referred to above means "as + affected by refraction". + + 2) Uses Hardie's (1962) polynomial fit to Bemporad's data for + the relative air mass, X, in units of thickness at the zenith + as tabulated by Schoenberg (1929). This is adequate for all + normal needs as it is accurate to better than 0.1% up to X = + 6.8 and better than 1% up to X = 10. Bemporad's tabulated + values are unlikely to be trustworthy to such accuracy + because of variations in density, pressure and other + conditions in the atmosphere from those assumed in his work. + + 3) The sign of the ZD is ignored. + + 4) At zenith distances greater than about ZD = 87 degrees the + air mass is held constant to avoid arithmetic overflows. + + References: + Hardie, R.H., 1962, in "Astronomical Techniques" + ed. W.A. Hiltner, University of Chicago Press, p180. + Schoenberg, E., 1929, Hdb. d. Ap., + Berlin, Julius Springer, 2, 268. + + Original code by P.W.Hill, St Andrews + + P.T.Wallace Starlink 18 March 1999 + + Copyright (C) 1999 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp -- cgit