some obs...

guide/app_ssystem_ini.tex

@@ -322,12 +322,12 @@ \subsection{File ssystem\_minor.ini}
 
 Orbital elements for minor bodies are always given for a particular
 \indexterm{equinox} like J2000.0 (which indicates the coordinate
-reference system) and \indexterm{epoch} (date). The other planets pull
-on the objects and change their orbits, most usually leading to the
+reference system) and \indexterm{epoch} (date). Other bodies pull
+on these objects and change their orbits, most usually leading to the
 objects appearing too early or too late in their orbits, but also
 changing the other orbital elements. In addition, outgassing events of
-comets can act like jet propulsion and change orbits in unpredictable
-ways.  It is heavily recommended to update the orbital elements on a
+comets and other phenomena (such as the Yarkovsky effect) can change orbits in unpredictable
+ways.  It is therefore crucial to update the orbital elements on a
 regular basis ($2\times$/year?), or at least before you go out and are
 actually observing minor bodies.  Use the Solar System Editor plugin
 for this task (section~\ref{sec:plugins:SolarSystemEditor}).
@@ -349,8 +349,8 @@ \subsection{File ssystem\_minor.ini}
 \item[orbit\_Epoch] JDE when these elements are valid. Defaults to
   2451545.0 = the J2000.0 standard epoch.
 
-\item[orbit\_good] can be given in days to limit computation of the
-  object to the time range
+\item[orbit\_good] [days] is an optional property to limit computation of the
+  object to the time range before/after the epoch.
   $\mathtt{epoch}\pm\mathtt{orbit\_good}$. If\newFeature{0.21.3}
   specified as \texttt{0} there is no check for out-of-range dates. If
   specified as \texttt{-1}, half the orbital period is used. The main
@@ -365,7 +365,7 @@ \subsection{File ssystem\_minor.ini}
 \item[orbit\_SemiMajorAxis] $a$ [AU]
 \item[orbit\_visualization\_period] [days] %TODO does that default to sth meaningful? Do we need it at all?
 \end{description}
-The other parameters are like those for the major planets. 
+The other parameters are similar to those for the major planets. 
 
 \subsubsection{Minor Planet section}
 \label{sec:ssystem.ini:MinorPlanet}
@@ -451,7 +451,7 @@ \subsubsection{Comet section}
 which is more typical for comets which may have no orbital period when
 they are on parabolic or hyperbolic orbits. Frequently orbital
 elements are given for a date very close to perihelion so that the
-perihel date can be used as default for the optional
+perihelion date can be used as default for the optional
 \texttt{orbit\_Epoch}. However, this assumption does not always hold,
 so we\newFeature{0.21.3} recommend to state \texttt{orbit\_Epoch} explicitly.
 

plugins/SolarSystemEditor/src/SolarSystemEditor.cpp

@@ -552,7 +552,7 @@ SsoElements SolarSystemEditor::readMpcOneLineCometElements(QString oneLineElemen
 	// result.insert("coord_func", "kepler_orbit"); // 0.20: omit default
 	result.insert("coord_func", "comet_orbit"); // 0.20: add this default for compatibility with earlier versions!
 	// GZ: moved next line below!
-	//result.insert("orbit_good", 1000); // default validity for osculating elements, days
+	//result.insert("orbit_good", KeplerOrbit::defaultOrbitGood_days); // default validity for osculating elements, days
 
 	//result.insert("color", "1.0, 1.0, 1.0");  // 0.16: omit obvious default.
 	//result.insert("tex_map", "nomap.png");    // 0.16: omit obvious default.
@@ -598,10 +598,10 @@ SsoElements SolarSystemEditor::readMpcOneLineCometElements(QString oneLineElemen
 		const double a=perihelionDistance/(1.-eccentricity); // semimajor axis.
 		const double meanMotion=std::sqrt(mu/(a*a*a)); // radians/day
 		double period=M_PI*2.0 / meanMotion; // period, days
-		result.insert("orbit_good", qMin(1000, static_cast<int>(floor(0.5*period)))); // validity for elliptical osculating elements, days. Goes from aphel to next aphel or max 1000 days.		
+		result.insert("orbit_good", qMin(KeplerOrbit::defaultOrbitGood_days, static_cast<int>(floor(0.5*period)))); // validity for elliptical osculating elements, days. Goes from aphel to next aphel or max KeplerOrbit::defaultOrbitGood_days days.		
 	}
 	else
-		result.insert("orbit_good", 1000); // default validity for osculating elements, days
+		result.insert("orbit_good", KeplerOrbit::defaultOrbitGood_days); // default validity for osculating elements, days
 
 	double absoluteMagnitude = mpcParser.cap(15).toDouble(&ok);
 	result.insert("absolute_magnitude", absoluteMagnitude);
@@ -832,12 +832,12 @@ SsoElements SolarSystemEditor::readMpcOneLineMinorPlanetElements(QString oneLine
 	result.insert("orbit_MeanAnomaly", meanAnomalyAtEpoch);
 	// We assume from now on that orbit_good is 1/2 orbital duration for elliptical orbits if not given explicitly.
 	// This allows following full ellipses. However, elsewhere we should signal to users when
-	// it should be assumed that elements are outdated and thus positions wrong. (Let's take "1000 earth days" for that.)
+	// it should be assumed that elements are outdated and thus positions wrong. (Let's take "KeplerOrbit::defaultOrbitGood_days earth days" for that.)
 	if (eccentricity >=1.)
 	{
 	    // This should actually never happen for minor planets!
 	    qWarning() << "Strange eccentricity for " << name << ":" << eccentricity;
-	    result.insert("orbit_good", 1000); // default validity for osculating elements for parabolic/hyperbolic comets, days
+	    result.insert("orbit_good", KeplerOrbit::defaultOrbitGood_days); // use default validity for osculating elements for parabolic/hyperbolic comets, days
 	}
 
 	// add period for visualization of orbit

src/core/modules/Orbit.cpp

@@ -40,6 +40,8 @@ using namespace std;
 #define cbrt(x) pow((x),1./3.)
 #endif
 
+const int KeplerOrbit::defaultOrbitGood_days = 3*365;
+
 //! Solve true anomaly nu for hyperbolic "orbit" (better: trajectory) around the sun.
 //! @param dt: days from perihel
 //! @param rCosNu: r*cos(nu)
@@ -155,10 +157,10 @@ KeplerOrbit::KeplerOrbit(double epochJDE,
 {
 	// For Comets and Minor planets, this just builds a unity matrix. For moons, it rotates into the equatorial system of the parent planet
 	setParentOrientation(parentRotObliquity, parentRotAscendingnode, parentRotJ2000Longitude);
-	if (orbitGood<0.)
+	if (orbitGood < e_orbit_valid)
 	{
-	    const double period=calculateSiderealPeriod();
-	    orbitGood=(period==0. ? 1000. : period*0.5);
+	    const double period = calculateSiderealPeriod();
+	    orbitGood = (period==0. ? KeplerOrbit::defaultOrbitGood_days : period*0.5);
 	}
 }
 
@@ -274,10 +276,10 @@ Vec2d KeplerOrbit::objectDateValidRange() const
 {
 	double min=std::numeric_limits<double>::min();
 	double max=std::numeric_limits<double>::max();
-	if (orbitGood>0)
+	if (orbitGood > e_orbit_valid)
 	{
-		min=epochJDE-orbitGood;
-		max=epochJDE+orbitGood;
+		min = epochJDE - orbitGood;
+		max = epochJDE + orbitGood;
 	}
 	return Vec2d(min, max);
 }

src/core/modules/Orbit.hpp

@@ -61,6 +61,12 @@ class Orbit
 //!   - Heafner: Fundamental Ephemeris Computations 1999
 class KeplerOrbit : public Orbit {
 public:
+
+	enum E_orbit_quality {
+		e_orbit_valid 		= 0, // XXX do not change this value... (smelly!)
+		e_orbit_always_good 	= -1 // e.g. moons/natural satellites
+	};
+
     //! Constructor.
     //! @param epochJDE                JDE epoch of orbital elements.
     //! @param pericenterDistance      [AU] pericenter distance
@@ -70,8 +76,8 @@ class KeplerOrbit : public Orbit {
     //! @param argOfPerhelion          [radians]
     //! @param timeAtPerihelion        JDE
     //! @param orbitGoodDays           [earth days] can be used to exclude computation for dates too far outside epoch.
-    //!                                 0: always good (use that for planet moons. Not really correct, but most users won't care)
-    //!                                -1: signal "auto-compute to 1/2 the orbital period or 1000 days if there is no period [e>=1]")
+    //!                                 0 XXX ????? : always ? good (used for natural satellites. Not really correct, but most users won't care)
+    //!                                -1: signal "auto-compute to 1/2 the orbital period or defaultOrbitGood_days days if there is no period [e>=1]")
     //! @param meanMotion              [radians/day] for parabolics, this is W/dt in Heafner's lettering
     //! @param parentRotObliquity      [radians] Comets/Minor Planets only have parent==sun, no need for these? --> Oh yes, these relate VSOP/J2000 eq frames!
     //! @param parentRotAscendingnode  [radians]
@@ -104,7 +110,7 @@ class KeplerOrbit : public Orbit {
 	//! Returns semimajor axis [AU] for elliptic orbit, 0 for a parabolic orbit, and a negative value [AU] for hyperbolic orbit.
 	virtual double getSemimajorAxis() const Q_DECL_OVERRIDE { return (e==1. ? 0. : q / (1.-e)); }
 	virtual double getEccentricity() const Q_DECL_OVERRIDE { return e; }
-	bool objectDateValid(const double JDE) const { return ((orbitGood==0.) || (fabs(epochJDE-JDE)<orbitGood)); }
+	bool objectDateValid(const double JDE) const { return ((orbitGood == e_orbit_valid) || (fabs(epochJDE-JDE)<orbitGood)); }
 	//! Return minimal and maximal JDE values where this orbit should be used. (if orbitGood is configured)
 	Vec2d objectDateValidRange() const;
 	//! Calculate sidereal period in days from semi-major axis and central mass. If SMA<=0 (hyperbolic orbit), return 0.
@@ -113,6 +119,9 @@ class KeplerOrbit : public Orbit {
 	//! @param centralMass in units of Solar masses
 	static double calculateSiderealPeriod(const double semiMajorAxis, const double centralMass);
 
+	//! range around epoch within which the orbit elements can be considered accurate enough
+	static const int defaultOrbitGood_days;
+
 private:
 	const double epochJDE; //!< epoch (date of validity) of the elements.
 	const double q;  //!< pericenter distance [AU]

src/core/modules/Planet.cpp

@@ -646,7 +646,7 @@ QString Planet::getInfoString(const StelCore* core, const InfoStringGroup& flags
 	oss << getInfoStringExtra(core, flags);
 	if (!hasValidPositionalData(core->getJDE()))
 	{
-	    oss << q_("NOTE: orbital elements outdated -- consider updating!") << "<br/>";
+	    oss << q_("*** orbital elements outdated -- consider updating!") << "<br/>";
 	}
 	postProcessInfoString(str, flags);
 	return str;
@@ -991,7 +991,7 @@ QString Planet::getInfoStringExtra(const StelCore *core, const InfoStringGroup&
 			}
 			else if (re.period==0.)
 			{
-				oss << q_("The period of rotation is chaotic") << "<br />";
+				oss << q_("The period of rotation is chaotic") << "<br/>";
 			}
 			if (qAbs(re.W1)>0.)
 			{
@@ -1057,7 +1057,7 @@ QString Planet::getInfoStringExtra(const StelCore *core, const InfoStringGroup&
 			oss << QString("%1: %2 %3").arg(q_("Moon age"), QString::number(age, 'f', 1), q_("days old"));
 			if (!moonPhase.isEmpty())
 				oss << QString(" (%4)").arg(moonPhase);
-			oss << "<br />";
+			oss << "<br/>";
 
 			if (useTopocentric)
 			{
@@ -1077,7 +1077,8 @@ QString Planet::getInfoStringExtra(const StelCore *core, const InfoStringGroup&
 				oss << QString("<tr><td colspan=\"2\">%1:</td><td align=\"right\"> %2</td></tr>").arg(q_("Position angle of bright limb"), chiStr);
 			}
 			else
-				oss << QString("%1: %2<br/>").arg(q_("Position angle of bright limb"), chiStr);
+				oss << QString("%1: %2").arg(q_("Position angle of bright limb"), chiStr);
+			oss << "<br/>";
 
 			// Everything around libration
 			const QStringList compassDirs={
@@ -1146,7 +1147,7 @@ QString Planet::getInfoStringExtra(const StelCore *core, const InfoStringGroup&
 				oss << QString("<tr><td>%1:</td><td align=\"right\">L: %2</td><td align=\"right\">B: %3</td></tr>").arg(q_("Libration"), libLStr, libBStr);
 				oss << QString("<tr><td>%1:</td><td align=\"right\">L<sub>s</sub>: %2</td><td align=\"right\">B<sub>s</sub>: %3</td></tr>").arg(q_("Subsolar point"), subsolarLStr, subsolarBStr);
 				oss << QString("<tr><td>%1:</td><td align=\"right\">c<sub>0</sub>: %2</td></tr>").arg(q_("Colongitude"), colongitudeStr);
-				oss << "</table>";
+				oss << "</table><br/>";
 			}
 			else
 			{
@@ -1189,7 +1190,7 @@ QString Planet::getInfoStringExtra(const StelCore *core, const InfoStringGroup&
 				oss << QString("<tr><td colspan=\"2\">%1:</td><td align=\"right\"> %2</td></tr>").arg(q_("Position Angle of axis"), paAxisStr);
 				oss << QString("<tr><td>%1:</td><td align=\"right\">L<sub>%2e</sub>: %3</td><td align=\"right\">&phi;<sub>e</sub>: %4</td></tr>").arg(q_("Center point"),   lngSystem, subearthLStr, subearthBStr);
 				oss << QString("<tr><td>%1:</td><td align=\"right\">L<sub>%2s</sub>: %3</td><td align=\"right\">&phi;<sub>s</sub>: %4</td></tr>").arg(q_("Subsolar point"), lngSystem, subsolarLStr, subsolarBStr);
-				oss << "</table>";
+				oss << "</table><br/>";
 			}
 			else
 			{

src/core/modules/SolarSystem.cpp

@@ -851,7 +851,8 @@ bool SolarSystem::loadPlanets(const QString& filePath)
 				parent_rot_j2000_longitude = atan2(J2000NodeOrigin*OrbitAxis1,J2000NodeOrigin*OrbitAxis0);
 			}
 
-			const double orbitGoodDays=pd.value(secname+"/orbit_good", parent->englishName!="Sun" ? 0. : -1.).toDouble(); // "Moons" have permanently good orbits.
+			const bool isNaturalSatellite = parent->englishName != "Sun";
+			const double orbitGoodDays = pd.value(secname+"/orbit_good", isNaturalSatellite ? KeplerOrbit::e_orbit_valid : KeplerOrbit::e_orbit_always_good /* sure ? */ ).toDouble(); // "Moons" have permanently good orbits.
 			const double inclination = pd.value(secname+"/orbit_Inclination", 0.0).toDouble()*(M_PI/180.0);
 
 			// Create a Keplerian orbit. This has been called CometOrbit before 0.20.
@@ -863,7 +864,7 @@ bool SolarSystem::loadPlanets(const QString& filePath)
 							   ascending_node,         // [radians]
 							   arg_of_pericenter,      // [radians]
 							   time_at_pericenter,     // JDE
-							   orbitGoodDays,          // orbitGoodDays. 0=always good, -1=compute_half_orbit_duration
+							   orbitGoodDays,          // orbitGoodDays. 0=always good? or just valid?, -1=compute_half_orbit_duration
 							   meanMotion,             // [radians/day]
 							   parentRotObliquity,     // [radians]
 							   parent_rot_asc_node,    // [radians]