From fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 8 Jul 2015 20:46:52 -0400 Subject: Initial commit --- math/slalib/rverot.f | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 math/slalib/rverot.f (limited to 'math/slalib/rverot.f') diff --git a/math/slalib/rverot.f b/math/slalib/rverot.f new file mode 100644 index 00000000..3fc5ab50 --- /dev/null +++ b/math/slalib/rverot.f @@ -0,0 +1,66 @@ + REAL FUNCTION slRVER (PHI, RA, DA, ST) +*+ +* - - - - - - - +* R V E R +* - - - - - - - +* +* Velocity component in a given direction due to Earth rotation +* (single precision) +* +* Given: +* PHI real latitude of observing station (geodetic) +* RA,DA real apparent RA,DEC +* ST real local apparent sidereal time +* +* PHI, RA, DEC and ST are all in radians. +* +* Result: +* Component of Earth rotation in direction RA,DA (km/s) +* +* Sign convention: +* The result is +ve when the observatory is receding from the +* given point on the sky. +* +* Accuracy: +* The simple algorithm used assumes a spherical Earth, of +* a radius chosen to give results accurate to about 0.0005 km/s +* for observing stations at typical latitudes and heights. For +* applications requiring greater precision, use the routine +* slPVOB. +* +* P.T.Wallace Starlink 20 July 1994 +* +* Copyright (C) 1995 Rutherford Appleton Laboratory +* +* License: +* This program is free software; you can redistribute it and/or modify +* it under the terms of the GNU General Public License as published by +* the Free Software Foundation; either version 2 of the License, or +* (at your option) any later version. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU General Public License for more details. +* +* You should have received a copy of the GNU General Public License +* along with this program (see SLA_CONDITIONS); if not, write to the +* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, +* Boston, MA 02110-1301 USA +* +* Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. +*- + + IMPLICIT NONE + + REAL PHI,RA,DA,ST + +* Nominal mean sidereal speed of Earth equator in km/s (the actual +* value is about 0.4651) + REAL ESPEED + PARAMETER (ESPEED=0.4655) + + + slRVER=ESPEED*COS(PHI)*SIN(ST-RA)*COS(DA) + + END -- cgit