Satellites: Restore shadow circle at arbitrary altitude

guide/ch_astronomical_phenomena.tex

@@ -991,10 +991,10 @@ \subsection{Lunar Eclipses}
 of the Solar disk is occulted by Earth, this spot on the Lunar surface
 will receive less sunlight and will appear darker when observed from
 Earth. A rule of thumb says that 70\% of the Moon must enter the
-Earth's penumbra before a light defect can be noted by attentive human
+Earth's \indexterm{penumbra} (partial shadow) before a light defect can be noted by attentive human
 observers. 
 
-The Earth's deep shadow is then much darker. As soon as an observer on
+The Earth's \indexterm{umbra} (deep shadow) is then much darker. As soon as an observer on
 the Lunar edge experiences a Total Solar eclipse, observers on Earth
 see the begin of the partial eclipse.
 

guide/plg_catalogs.tex

@@ -1205,9 +1205,9 @@ \section{Satellites Plugin}
 	\label{fig:plugins:Satellites:Configuration}
 \end{figure}
 
-If the plugin has been enabled (see
+\noindent If the plugin has been enabled (see
 section~\ref{sec:Plugins:EnablingPlugins}), just click on the
-Satellite button \guibutton{0.6}{bt_hint.png}  on the bottom
+Satellite button \guibutton{0.6}{bt_satellites_off.png}  on the bottom
 toolbar to display markers for the satellites, or use right click to call the GUI.
 
 You can search for artificial satellites using
@@ -1220,10 +1220,10 @@ \section{Satellites Plugin}
 the huge number of satellites in orbit, most of which are invisible to
 the unaided eye.
 
-You can display \newFeature{0.22.2} circles representing the Earth's
+You can display\newFeature{0.22.2} circles representing the Earth's
 shadow (penumbra and umbra, defined just like for Lunar eclipses, see
-section~\ref{sec:Eclipses:lunar}), at the distance of the currently
-selected satellite, or at a fixed (configurable) distance from Earth's surface.
+section~\ref{sec:Eclipses:lunar}), at the altitude of the currently
+selected satellite, or at a fixed (configurable) altitude from Earth's surface.
 
 \subsection{Satellite Properties}
 \label{sec:plugins:Satellites:properties}
@@ -1309,7 +1309,7 @@ \subsection{Satellite Properties}
 	\label{fig:plugins:Satellites:Configuration:SatellitesFilter}
 \end{figure}
 
-You can display \newFeature{0.22.2} a list of satellites by specific
+You can display\newFeature{0.22.2} a list of satellites by specific
 selection of their properties, when the filter ``[custom filter]'' has
 been selected (Fig.~\ref{fig:plugins:Satellites:Configuration:SatellitesFilter}). The
 settings of this filter are available through the button

plugins/Satellites/src/Satellite.cpp

@@ -448,7 +448,7 @@ QString Satellite::getInfoString(const StelCore *core, const InfoStringGroup& fl
 		//Visibility: Full text		
 		oss << q_(visibilityDescription.value(visibility, "")) << "<br />";
 
-		if (!comms.isEmpty())
+		if (!comms.isEmpty() && (status!=Satellite::StatusNonoperational))
 		{
 			oss << q_("Radio communication") << ":<br/>";
 			for (const auto& c : comms)
@@ -469,7 +469,6 @@ QString Satellite::getInfoString(const StelCore *core, const InfoStringGroup& fl
 QString Satellite::getCommLinkInfo(CommLink comm) const
 {
 	QString commLinkData;
-
 	if (!comm.modulation.isEmpty()) // OK, the signal modulation mode is exist
 		commLinkData = comm.modulation;
 
@@ -502,7 +501,6 @@ QString Satellite::getCommLinkInfo(CommLink comm) const
 		sign='+';
 
 	commLinkData.append(QString(": %1 %2 (%3%4 %5)<br />").arg(QString::number(comm.frequency, 'f', 3), qc_("MHz", "frequency"), sign, QString::number(ddop, 'f', 3), qc_("kHz", "frequency")));
-
 	return commLinkData;
 }
 
@@ -827,7 +825,7 @@ void Satellite::update(double)
 		perigee                  = pa[0];
 		apogee                   = pa[1];
 		*/
-		if (height < 100) // below Kármán line: Satellite is certainly lost, at least TLE not applicable.
+		if (height < 80) // way below Kármán line: Satellite is certainly lost, at least TLE not applicable.
 		{
 			// The orbit is no longer valid.  Causes include very out of date
 			// TLE, system date and time out of a reasonable range, and orbital
@@ -890,6 +888,7 @@ Vec4d Satellite::getUmbraData()
 	penumbraDistance=rhoE*cos(muP);
 	// radius of shadow circle
 	penumbraRadius=rhoE*sin(muP);
+	//// DBG out
 	//StelObjectMgr *om=GETSTELMODULE(StelObjectMgr);
 	//om->setExtraInfoString(StelObject::DebugAid, QString("&rho;<sub>E</sub> %1, r<sub>S</sub> %2, &theta;<sub>E</sub> %3°, &theta;<sub>S</sub> %4° <br/>")
 	//		       .arg(QString::number(rhoE, 'f', 3),
@@ -917,6 +916,75 @@ Vec4d Satellite::getUmbraData()
 	return Vec4d(umbraDistance, umbraRadius, penumbraDistance, penumbraRadius);
 }
 
+//! Get radii and geocentric distances of shadow circles in km for a hypothetical object in dist_km above the (spherical) Earth.
+//! Vec4d(umbraDistance, umbraRadius, penumbraDistance, penumbraRadius);
+Vec4d Satellite::getUmbraData(double dist_km)
+{
+	static PlanetP earth=GETSTELMODULE(SolarSystem)->getEarth();
+	static PlanetP sun = GETSTELMODULE(SolarSystem)->getSun();
+
+	// Compute altitudes of umbra and penumbra circles. These should show where the satellite enters/exits umbra/penumbra.
+	// The computation follows ideas from https://celestrak.org/columns/v03n01/
+	// These sources mention ECI coordinates (Earth Centered Inertial). Presumably TEME (True Equator Mean Equinox) are equivalent, at least for our purposes.
+	const double rhoE=earth->getEquatorialRadius()*AU+dist_km; // geocentric Satellite distance, km
+	const double rS=earth->getHeliocentricEclipticPos().norm()*AU; // distance earth...sun
+	const double thetaE=asin((earth->getEquatorialRadius()*AU)/(rhoE));
+	// Accurate distance sat...sun from ECI sunpos
+	//Vec3d sunTEME=pSatWrapper->getSunECIPos() - pSatWrapper->getObserverECIPos(); // km
+	Vec3d sunEquinoxEqPos = sun->getEquinoxEquatorialPos(StelApp::getInstance().getCore());
+	Vec3d sunTEME=sunEquinoxEqPos*AU;
+	const double thetaS=asin((sun->getEquatorialRadius()*AU)/(sunTEME.norm()));
+	Q_ASSERT(thetaE>thetaS);
+	const double theta=thetaE-thetaS; // angle so that satellite dives into umbra
+	// angle at Sun:
+	const double sigma=asin(sin(theta)*rhoE/rS);
+	// angle in geocenter
+	const double eta=M_PI-sigma-theta;
+	// complement
+	const double mu=M_PI-eta;
+	// geocentric distance of shadow circle towards antisun
+	double umbraDistance=rhoE*cos(mu);
+	// radius of shadow circle
+	double umbraRadius=rhoE*sin(mu);
+	// Repeat for penumbra
+	const double thetaP=thetaE+thetaS; // angle so that satellite touches penumbra
+	// angle at Sun:
+	const double sigmaP=asin(sin(thetaP)*rhoE/rS);
+	// angle in geocenter
+	const double etaP=M_PI-sigmaP-thetaP;
+	// complement
+	const double muP=M_PI-etaP;
+	// geocentric distance of shadow circle towards antisun
+	double penumbraDistance=rhoE*cos(muP);
+	// radius of shadow circle
+	double penumbraRadius=rhoE*sin(muP);
+	//// DBG OUT
+	//StelObjectMgr *om=GETSTELMODULE(StelObjectMgr);
+	//om->setExtraInfoString(StelObject::DebugAid, QString("&rho;<sub>E</sub> %1, r<sub>S</sub> %2, &theta;<sub>E</sub> %3°, &theta;<sub>S</sub> %4° <br/>")
+	//		       .arg(QString::number(rhoE, 'f', 3),
+	//			    QString::number(rS, 'f', 3),
+	//			    QString::number(thetaE*M_180_PI, 'f', 3),
+	//			    QString::number(thetaS*M_180_PI, 'f', 3)
+	//			    )
+	//		       );
+	//om->addToExtraInfoString(StelObject::DebugAid, QString("&theta; %1°, &sigma; %2°, &eta; %3°, &mu; %4° <br/>")
+	//		       .arg(
+	//			    QString::number(theta*M_180_PI, 'f', 3),
+	//			    QString::number(sigma*M_180_PI, 'f', 3),
+	//			    QString::number(eta*M_180_PI, 'f', 3),
+	//			    QString::number(mu*M_180_PI, 'f', 3)
+	//			    )
+	//		       );
+	//om->addToExtraInfoString(StelObject::DebugAid, QString("&theta;<sub>P</sub> %1°, &sigma; %2°, &eta; %3°, &mu; %4° <br/>")
+	//		       .arg(
+	//			    QString::number(thetaP*M_180_PI, 'f', 3),
+	//			    QString::number(sigmaP*M_180_PI, 'f', 3),
+	//			    QString::number(etaP*M_180_PI, 'f', 3),
+	//			    QString::number(muP*M_180_PI, 'f', 3)
+	//			    )
+	//		       );
+	return Vec4d(umbraDistance, umbraRadius, penumbraDistance, penumbraRadius);
+}
 
 double Satellite::getDoppler(double freq) const
 {

plugins/Satellites/src/Satellite.hpp

@@ -249,6 +249,10 @@ class Satellite : public StelObject
 	//! Vec4d(umbraDistance, umbraRadius, penumbraDistance, penumbraRadius);
 	Vec4d getUmbraData();
 
+	//! Get radii and geocentric distances of shadow circles in km for a hypothetical object in dist_km above the (spherical) Earth.
+	//! Vec4d(umbraDistance, umbraRadius, penumbraDistance, penumbraRadius);
+	static Vec4d getUmbraData(double dist_km);
+
 	//! Get operational status of satellite
 	QString getOperationalStatus() const;
 

plugins/Satellites/src/Satellites.cpp

@@ -97,12 +97,11 @@ Satellites::Satellites()
 	, autoRemoveEnabled(false)
 	, updateFrequencyHours(0)
 	, flagUmbraVisible(false)
-	, flagUmbraAtFixedDistance(false)
+	, flagUmbraAtFixedAltitude(false)
 	, umbraColor(1.0f, 0.0f, 0.0f)
-	, fixedUmbraDistance(1000.0)
+	, fixedUmbraAltitude(1000.0)
 	, flagPenumbraVisible(false)
 	, penumbraColor(1.0f, 0.0f, 0.0f)
-	, earthShadowEnlargementDanjon(false)
 	, lastSelectedSatellite(QString())
 	#if(SATELLITES_PLUGIN_IRIDIUM == 1)
 	, iridiumFlaresPredictionDepth(7)
@@ -228,7 +227,6 @@ void Satellites::init()
 	connect(core, SIGNAL(locationChanged(StelLocation)), this, SLOT(updateObserverLocation(StelLocation)));
 	connect(core, SIGNAL(configurationDataSaved()), this, SLOT(saveSettings()));
 	connect(&StelApp::getInstance(), SIGNAL(languageChanged()), this, SLOT(translateData()));
-	connect(ssystem, SIGNAL(earthShadowEnlargementDanjonChanged(bool)), this, SLOT(updateEarthShadowEnlargementFlag(bool)));
 
 	connect(this, SIGNAL(satSelectionChanged(QString)), this, SLOT(changeSelectedSatellite(QString)));
 
@@ -689,9 +687,9 @@ void Satellites::restoreDefaultSettings()
 	conf->setValue("hide_invisible_satellites", false);
 	conf->setValue("colored_invisible_satellites", true);
 	conf->setValue("umbra_flag", false);
-	conf->setValue("umbra_fixed_distance_flag", false);
+	conf->setValue("umbra_fixed_altitude_flag", false);
 	conf->setValue("umbra_color", "1.0,0.0,0.0");
-	conf->setValue("umbra_fixed_distance", 1000.0);
+	conf->setValue("umbra_fixed_altitude", 1000.0);
 	conf->setValue("penumbra_flag", false);
 	conf->setValue("penumbra_color", "1.0,0.0,0.0");
 	conf->setValue("cf_magnitude_flag", false);
@@ -834,11 +832,9 @@ void Satellites::loadSettings()
 
 	// umbra/penumbra
 	setFlagUmbraVisible(conf->value("umbra_flag", false).toBool());
-	// FIXME: Repair the functionality!
-	setFlagUmbraAtFixedDistance(false);
-	//setFlagUmbraAtFixedDistance(conf->value("umbra_fixed_distance_flag", false).toBool());
+	setFlagUmbraAtFixedAltitude(conf->value("umbra_fixed_altitude_flag", false).toBool());
 	setUmbraColor(Vec3f(conf->value("umbra_color", "1.0,0.0,0.0").toString()));
-	setUmbraDistance(conf->value("umbra_fixed_distance", 1000.0).toDouble());
+	setUmbraAltitude(conf->value("umbra_fixed_altitude", 1000.0).toDouble());
 	setFlagPenumbraVisible(conf->value("penumbra_flag", false).toBool());
 	setPenumbraColor(Vec3f(conf->value("penumbra_color", "1.0,0.0,0.0").toString()));
 
@@ -930,11 +926,9 @@ void Satellites::saveSettingsToConfig()
 
 	// umbra/penumbra
 	conf->setValue("umbra_flag", getFlagUmbraVisible());
-	// FIXME: Fix and re-enable this function
-	//conf->setValue("umbra_fixed_distance_flag", getFlagUmbraAtFixedDistance());
-	conf->setValue("umbra_fixed_distance_flag", false); // Preliminary
+	conf->setValue("umbra_fixed_altitude_flag", getFlagUmbraAtFixedAltitude());
 	conf->setValue("umbra_color", getUmbraColor().toStr());
-	conf->setValue("umbra_fixed_distance", getUmbraDistance());
+	conf->setValue("umbra_fixed_altitude", getUmbraAltitude());
 	conf->setValue("penumbra_flag", getFlagPenumbraVisible());
 	conf->setValue("penumbra_color", getPenumbraColor().toStr());
 
@@ -1911,18 +1905,14 @@ void Satellites::setFlagUmbraVisible(bool b)
 	}
 }
 
-void Satellites::setFlagUmbraAtFixedDistance(bool b)
+void Satellites::setFlagUmbraAtFixedAltitude(bool b)
 {
-	flagUmbraAtFixedDistance = false;
-	qDebug() << "setFlagUmbraAtFixedDistance() currently not possible";
-
-	// TO BE FIXED
-	//if (flagUmbraAtFixedDistance != b)
-	//{
-	//	flagUmbraAtFixedDistance = b;
-	//	emit settingsChanged(); // GZ IS THIS REQUIRED/USEFUL??
-	//	emit flagUmbraAtFixedDistanceChanged(b);
-	//}
+	if (flagUmbraAtFixedAltitude != b)
+	{
+		flagUmbraAtFixedAltitude = b;
+		emit settingsChanged(); // GZ IS THIS REQUIRED/USEFUL??
+		emit flagUmbraAtFixedAltitudeChanged(b);
+	}
 }
 
 void Satellites::setUmbraColor(const Vec3f &c)
@@ -1931,10 +1921,10 @@ void Satellites::setUmbraColor(const Vec3f &c)
 	emit umbraColorChanged(c);
 }
 
-void Satellites::setUmbraDistance(double d)
+void Satellites::setUmbraAltitude(double d)
 {
-	fixedUmbraDistance = d;
-	emit umbraDistanceChanged(d);
+	fixedUmbraAltitude = d;
+	emit umbraAltitudeChanged(d);
 }
 
 void Satellites::setFlagPenumbraVisible(bool b)
@@ -2860,7 +2850,7 @@ void Satellites::drawCircles(StelCore* core, StelPainter &painter)
 	painter.setLineSmooth(true);
 	painter.setFont(labelFont);
 
-	double lambda, beta, umbraDistance_AU, umbraRadius_AU, penumbraDistance_AU, penumbraRadius_AU;
+	double lambda, beta;
 	const Vec3d pos = earth->getEclipticPos();
 	const Vec3d dir = - sun->getAberrationPush() + pos;
 	StelUtils::rectToSphe(&lambda, &beta, dir);
@@ -2871,47 +2861,26 @@ void Satellites::drawCircles(StelCore* core, StelPainter &painter)
 	if (!newSelected.empty())
 		sat = getById(newSelected[0].staticCast<Satellite>()->getCatalogNumberString());
 
-	if (flagUmbraAtFixedDistance)
+	Vec4d umbraData;
+	if (flagUmbraAtFixedAltitude)
 	{
-		umbraDistance_AU = penumbraDistance_AU = fixedUmbraDistance/AU+earth->getEquatorialRadius(); // geocentric circle distance [AU]
-		const double earthDistance=earth->getHeliocentricEclipticPos().norm(); // Earth distance [AU]
-		const double sunHP = asin(earth->getEquatorialRadius()/earthDistance)    * (M_180_PI*3600.); // arcsec.
-		const double satHP = asin(earth->getEquatorialRadius()/umbraDistance_AU) * (M_180_PI*3600.); // arcsec.
-		const double sunSD = atan(sun->getEquatorialRadius()/earthDistance)      * (M_180_PI*3600.); // arcsec.
-
-		//Classical Bessel elements
-		double f1, f2;
-		if (earthShadowEnlargementDanjon)
-		{
-			static const double danjonScale=1+1./85.-1./594.; // ~1.01, shadow magnification factor (see Espenak 5000 years Canon)
-			f1=danjonScale*satHP + sunHP + sunSD; // penumbra radius, arcsec
-			f2=danjonScale*satHP + sunHP - sunSD; // umbra radius, arcsec
-		}
-		else
-		{
-			const double mHP1=0.998340*satHP;
-			f1=1.02*(mHP1 + sunHP + sunSD); // penumbra radius, arcsec
-			f2=1.02*(mHP1 + sunHP - sunSD); // umbra radius, arcsec
-		}
-		penumbraRadius_AU=tan(f1/3600.*M_PI_180)*umbraDistance_AU;
-		umbraRadius_AU=tan(f2/3600.*M_PI_180)*umbraDistance_AU;
+		umbraData=Satellite::getUmbraData(fixedUmbraAltitude)/AU;
 	}
 	else if (!sat.isNull())
 	{
-		Vec4d umbraData=sat->getUmbraData();
-		umbraDistance_AU    = umbraData[0]/AU;
-		umbraRadius_AU      = umbraData[1]/AU;
-		penumbraDistance_AU = umbraData[2]/AU;
-		penumbraRadius_AU   = umbraData[3]/AU;
+		umbraData=sat->getUmbraData()/AU;
 	}
 	else
 		return;
 
-
+	const double umbraDistance_AU    = umbraData[0];
+	const double umbraRadius_AU      = umbraData[1];
+	const double penumbraDistance_AU = umbraData[2];
+	const double penumbraRadius_AU   = umbraData[3];
 	StelVertexArray umbra(StelVertexArray::LineLoop);
-	for (int i=0; i<360; ++i)
+	for (int i=0; i<4*360; ++i)
 	{
-		Vec3d point(umbraDistance_AU, cos(i*M_PI_180)*umbraRadius_AU, sin(i*M_PI_180)*umbraRadius_AU);
+		Vec3d point(umbraDistance_AU, cos(i*M_PI_180*0.25)*umbraRadius_AU, sin(i*M_PI_180*0.25)*umbraRadius_AU);
 		rot.transfo(point);
 		umbra.vertex.append(pos+point);
 	}
@@ -2924,16 +2893,17 @@ void Satellites::drawCircles(StelCore* core, StelPainter &painter)
 	rot.transfo(point);
 	Vec3d coord = pos+point;
 	painter.drawSprite2dMode(coord, 5.f);
-	QString cuLabel = QString("%1 (h=%2 %3)").arg(q_("C.U."), QString::number(AU*(umbraDistance_AU - earth->getEquatorialRadius()), 'f', 1), qc_("km","distance"));
+	QString number = QString::number( (getFlagUmbraAtFixedAltitude() ? getUmbraAltitude() : sat->latLongSubPointPosition[2] ), 'f', 1);
+	QString cuLabel = QString("%1 (h=%2 %3)").arg(q_("C.U."), number, qc_("km","distance"));
 	const float shift = 8.f;
 	painter.drawText(coord, cuLabel, 0, shift, shift, false);
 
 	if (getFlagPenumbraVisible())
 	{
 		StelVertexArray penumbra(StelVertexArray::LineLoop);
-		for (int i=0; i<360; ++i)
+		for (int i=0; i<4*360; ++i)
 		{
-			Vec3d point(penumbraDistance_AU, cos(i*M_PI_180)*penumbraRadius_AU, sin(i*M_PI_180)*penumbraRadius_AU);
+			Vec3d point(penumbraDistance_AU, cos(i*M_PI_180*0.25)*penumbraRadius_AU, sin(i*M_PI_180*0.25)*penumbraRadius_AU);
 			rot.transfo(point);
 			penumbra.vertex.append(pos+point);
 		}