_yData = new double[_targets.length][numSteps];
_yDataAirmass = new double[_targets.length][numSteps];
_yDataPa = new double[_targets.length][numSteps];
_skyCalc = new SkyCalc(_site);
// Set start of plot to noon time at the site, so night is at center
Calendar cal = Calendar.getInstance(_site.getTimeZone());
cal.setTime(_date);
cal.set(Calendar.HOUR_OF_DAY, 12); // noon