R/sunRTScalc2.R

In helixcn/ephem: Creating figures for astronomical almanac

sunRTScalc2 <-
function(JD, longitude, latitude, zone,
         type = c("rise", "transit", "set")) {
  type <- match.arg(type)

  SunDetails1 = CAAElliptical_Calculate_Sun(JD - 1)
  Alpha1 = SunDetails1$ApparentGeocentricRA;
  Delta1 = SunDetails1$ApparentGeocentricDeclination;

  SunDetails2 = CAAElliptical_Calculate_Sun(JD)
  Alpha2 = SunDetails2$ApparentGeocentricRA;
  Delta2 = SunDetails2$ApparentGeocentricDeclination;

  SunDetails3 = CAAElliptical_Calculate_Sun(JD + 1)
  Alpha3 = SunDetails3$ApparentGeocentricRA;
  Delta3 = SunDetails3$ApparentGeocentricDeclination;

  RiseTransitSetTime = CAARiseTransitSet_Calculate(JD,
        Alpha1, Delta1, Alpha2, Delta2, Alpha3, Delta3,
        longitude, latitude, -0.8333);

  switch(type,
    rise = {
    rtsJD = (JD + (RiseTransitSetTime$details.Rise / 24.00));
  },
    set = {
    rtsJD = (JD + (RiseTransitSetTime$details.Set / 24.00));
  },
    transit = {
    rtsJD = (JD + (RiseTransitSetTime$details.Transit / 24.00));
  }
    )
  lclJD = rtsJD - (zone / 24.00);

  names(lclJD) <- paste("Sun", type, sep = " ")
  return(lclJD)
}