private double CalculateSiderealTime() { double siderealTime = double.NaN; // Now using NOVAS 3.1 using (var novas = new ASCOM.Astrometry.NOVAS.NOVAS31()) { var jd = utilities.DateUTCToJulian(DateTime.UtcNow); novas.SiderealTime(jd, 0, novas.DeltaT(jd), ASCOM.Astrometry.GstType.GreenwichApparentSiderealTime, ASCOM.Astrometry.Method.EquinoxBased, ASCOM.Astrometry.Accuracy.Reduced, ref siderealTime); } // Allow for the longitude siderealTime += SiteLongitude / 360.0 * 24.0; // Reduce to the range 0 to 24 hours siderealTime = astroUtilities.ConditionRA(siderealTime); return(siderealTime); }