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17  package org.orekit.propagation.events;
18  
19  import java.util.List;
20  
21  import org.hipparchus.geometry.euclidean.threed.Vector3D;
22  import org.hipparchus.ode.events.Action;
23  import org.hipparchus.util.FastMath;
24  import org.junit.After;
25  import org.junit.Assert;
26  import org.junit.Before;
27  import org.junit.Test;
28  import org.orekit.Utils;
29  import org.orekit.bodies.BodyShape;
30  import org.orekit.bodies.GeodeticPoint;
31  import org.orekit.bodies.OneAxisEllipsoid;
32  import org.orekit.frames.Frame;
33  import org.orekit.frames.FramesFactory;
34  import org.orekit.frames.TopocentricFrame;
35  import org.orekit.models.AtmosphericRefractionModel;
36  import org.orekit.models.earth.EarthStandardAtmosphereRefraction;
37  import org.orekit.orbits.EquinoctialOrbit;
38  import org.orekit.orbits.KeplerianOrbit;
39  import org.orekit.orbits.Orbit;
40  import org.orekit.orbits.PositionAngle;
41  import org.orekit.propagation.Propagator;
42  import org.orekit.propagation.SpacecraftState;
43  import org.orekit.propagation.analytical.EcksteinHechlerPropagator;
44  import org.orekit.propagation.analytical.KeplerianPropagator;
45  import org.orekit.propagation.events.EventsLogger.LoggedEvent;
46  import org.orekit.propagation.events.handlers.ContinueOnEvent;
47  import org.orekit.propagation.events.handlers.EventHandler;
48  import org.orekit.propagation.events.handlers.StopOnIncreasing;
49  import org.orekit.propagation.sampling.OrekitFixedStepHandler;
50  import org.orekit.time.AbsoluteDate;
51  import org.orekit.time.TimeScale;
52  import org.orekit.time.TimeScalesFactory;
53  import org.orekit.utils.Constants;
54  import org.orekit.utils.ElevationMask;
55  import org.orekit.utils.IERSConventions;
56  import org.orekit.utils.PVCoordinates;
57  
58  public class ElevationDetectorTest {
59  
60      private double mu;
61      private double ae;
62      private double c20;
63      private double c30;
64      private double c40;
65      private double c50;
66      private double c60;
67  
68      @Test
69      public void testAgata() {
70  
71          final TimeScale utc = TimeScalesFactory.getUTC();
72          final Vector3D position = new Vector3D(-6142438.668, 3492467.56, -25767.257);
73          final Vector3D velocity = new Vector3D(505.848, 942.781, 7435.922);
74          final AbsoluteDate date = new AbsoluteDate(2003, 9, 16, utc);
75          final Orbit orbit = new EquinoctialOrbit(new PVCoordinates(position,  velocity),
76                                                   FramesFactory.getEME2000(), date, mu);
77  
78          Propagator propagator =
79              new EcksteinHechlerPropagator(orbit, ae, mu, c20, c30, c40, c50, c60);
80  
81          // Earth and frame
82          double ae =  6378137.0; // equatorial radius in meter
83          double f  =  1.0 / 298.257223563; // flattening
84          Frame itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true); // terrestrial frame at an arbitrary date
85          BodyShape earth = new OneAxisEllipsoid(ae, f, itrf);
86          GeodeticPoint point = new GeodeticPoint(FastMath.toRadians(48.833),
87                                                  FastMath.toRadians(2.333),
88                                                  0.0);
89          TopocentricFrame topo = new TopocentricFrame(earth, point, "Gstation");
90          Checking checking = new Checking(topo);
91          ElevationDetector detector =
92                  new ElevationDetector(topo).
93                  withConstantElevation(FastMath.toRadians(5.0)).
94                  withHandler(checking);
95          Assert.assertNull(detector.getElevationMask());
96          Assert.assertNull(detector.getRefractionModel());
97          Assert.assertSame(topo, detector.getTopocentricFrame());
98          Assert.assertEquals(FastMath.toRadians(5.0), detector.getMinElevation(), 1.0e-15);
99  
100         AbsoluteDate startDate = new AbsoluteDate(2003, 9, 15, 12, 0, 0, utc);
101         propagator.resetInitialState(propagator.propagate(startDate));
102         propagator.addEventDetector(detector);
103         propagator.setStepHandler(10.0, checking);
104         propagator.propagate(startDate.shiftedBy(Constants.JULIAN_DAY));
105 
106     }
107 
108     private static class Checking implements EventHandler<ElevationDetector>, OrekitFixedStepHandler {
109 
110         private TopocentricFrame topo;
111         private boolean visible;
112 
113         public Checking(final TopocentricFrame topo) {
114             this.topo = topo;
115             this.visible = false;
116         }
117 
118         public Action eventOccurred(SpacecraftState s, ElevationDetector detector, boolean increasing) {
119             visible = increasing;
120             return Action.CONTINUE;
121         }
122 
123         public void handleStep(SpacecraftState currentState)
124             {
125             BodyShape shape = topo.getParentShape();
126             GeodeticPoint p =
127                             shape.transform(currentState.getPVCoordinates().getPosition(),
128                                             currentState.getFrame(), currentState.getDate());
129             Vector3D subSat = shape.transform(new GeodeticPoint(p.getLatitude(), p.getLongitude(), 0.0));
130             double range = topo.getRange(subSat, shape.getBodyFrame(), currentState.getDate());
131 
132             if (visible) {
133                 Assert.assertTrue(range < 2.45e6);
134             } else {
135                 Assert.assertTrue(range > 2.02e6);
136             }
137         }
138 
139         @Override
140         public void init(SpacecraftState initialState, AbsoluteDate target, double step) {
141         }
142 
143     }
144 
145     @Test
146     public void testEventForMask() {
147 
148         final TimeScale utc = TimeScalesFactory.getUTC();
149         final Vector3D position = new Vector3D(-6142438.668, 3492467.56, -25767.257);
150         final Vector3D velocity = new Vector3D(505.848, 942.781, 7435.922);
151         final AbsoluteDate date = new AbsoluteDate(2003, 9, 16, utc);
152         final Orbit orbit = new EquinoctialOrbit(new PVCoordinates(position,  velocity),
153                                                  FramesFactory.getEME2000(), date, mu);
154 
155         Propagator propagator =
156             new EcksteinHechlerPropagator(orbit, ae, mu, c20, c30, c40, c50, c60);
157 
158         // Earth and frame
159         double ae =  6378137.0; // equatorial radius in meter
160         double f  =  1.0 / 298.257223563; // flattening
161         Frame itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true); // terrestrial frame at an arbitrary date
162         BodyShape earth = new OneAxisEllipsoid(ae, f, itrf);
163         GeodeticPoint point = new GeodeticPoint(FastMath.toRadians(48.833),
164                                                 FastMath.toRadians(2.333),
165                                                 0.0);
166         TopocentricFrame topo = new TopocentricFrame(earth, point, "Gstation");
167         double [][] maskValues = {{ FastMath.toRadians(  0), FastMath.toRadians(5)},
168                                   { FastMath.toRadians( 30), FastMath.toRadians(4)},
169                                   { FastMath.toRadians( 60), FastMath.toRadians(3)},
170                                   { FastMath.toRadians( 90), FastMath.toRadians(2)},
171                                   { FastMath.toRadians(120), FastMath.toRadians(3)},
172                                   { FastMath.toRadians(150), FastMath.toRadians(4)},
173                                   { FastMath.toRadians(180), FastMath.toRadians(5)},
174                                   { FastMath.toRadians(210), FastMath.toRadians(6)},
175                                   { FastMath.toRadians(240), FastMath.toRadians(5)},
176                                   { FastMath.toRadians(270), FastMath.toRadians(4)},
177                                   { FastMath.toRadians(300), FastMath.toRadians(3)},
178                                   { FastMath.toRadians(330), FastMath.toRadians(4)}};
179         ElevationMask mask = new ElevationMask(maskValues);
180         ElevationDetector detector = new ElevationDetector(topo)
181                                             .withElevationMask(mask)
182                                             .withHandler(new StopOnIncreasing<ElevationDetector>());
183         Assert.assertSame(mask, detector.getElevationMask());
184 
185         AbsoluteDate startDate = new AbsoluteDate(2003, 9, 15, 20, 0, 0, utc);
186         propagator.resetInitialState(propagator.propagate(startDate));
187         propagator.addEventDetector(detector);
188         final SpacecraftState fs = propagator.propagate(startDate.shiftedBy(Constants.JULIAN_DAY));
189         double elevation = topo.getElevation(fs.getPVCoordinates().getPosition(), fs.getFrame(), fs.getDate());
190         Assert.assertEquals(0.065, elevation, 2.0e-5);
191 
192     }
193 
194 
195     @Test
196     public void testHorizon() {
197 
198         final TimeScale utc = TimeScalesFactory.getUTC();
199         final Vector3D position = new Vector3D(-6142438.668, 3492467.56, -25767.257);
200         final Vector3D velocity = new Vector3D(505.848, 942.781, 7435.922);
201         final AbsoluteDate date = new AbsoluteDate(2003, 9, 16, utc);
202         final Orbit orbit = new EquinoctialOrbit(new PVCoordinates(position,  velocity),
203                                                  FramesFactory.getEME2000(), date, mu);
204 
205         Propagator propagator =
206             new EcksteinHechlerPropagator(orbit, ae, mu, c20, c30, c40, c50, c60);
207 
208         // Earth and frame
209         double ae =  6378137.0; // equatorial radius in meter
210         double f  =  1.0 / 298.257223563; // flattening
211         Frame itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true); // terrestrial frame at an arbitrary date
212         BodyShape earth = new OneAxisEllipsoid(ae, f, itrf);
213         GeodeticPoint point = new GeodeticPoint(FastMath.toRadians(48.833),
214                                                 FastMath.toRadians(2.333),
215                                                 0.0);
216         TopocentricFrame topo = new TopocentricFrame(earth, point, "Gstation");
217         AtmosphericRefractionModel refractionModel = new EarthStandardAtmosphereRefraction();
218         ElevationDetector detector = new ElevationDetector(topo)
219                                             .withRefraction(refractionModel)
220                                             .withHandler(new StopOnIncreasing<ElevationDetector>());
221         Assert.assertSame(refractionModel, detector.getRefractionModel());
222 
223         AbsoluteDate startDate = new AbsoluteDate(2003, 9, 15, 20, 0, 0, utc);
224         propagator.resetInitialState(propagator.propagate(startDate));
225         propagator.addEventDetector(detector);
226         final SpacecraftState fs = propagator.propagate(startDate.shiftedBy(Constants.JULIAN_DAY));
227         double elevation = topo.getElevation(fs.getPVCoordinates().getPosition(), fs.getFrame(), fs.getDate());
228         Assert.assertEquals(FastMath.toRadians(-0.5746255623877098), elevation, 2.0e-5);
229 
230     }
231 
232 
233     @Test
234     public void testIssue136() {
235 
236         //  Initial state definition : date, orbit
237         AbsoluteDate initialDate = new AbsoluteDate(2004, 01, 01, 23, 30, 00.000, TimeScalesFactory.getUTC());
238         Frame inertialFrame = FramesFactory.getEME2000(); // inertial frame for orbit definition
239         Orbit initialOrbit = new KeplerianOrbit(6828137.005, 7.322641382145889e-10, 1.6967079057368113,
240                                                 0.0, 1.658054062748353,
241                                                 0.0001223149429077902, PositionAngle.MEAN,
242                                                 inertialFrame, initialDate, Constants.EIGEN5C_EARTH_MU);
243 
244         // Propagator : consider a simple Keplerian motion (could be more elaborate)
245         Propagator kepler = new EcksteinHechlerPropagator(initialOrbit,
246                                                           Constants.EGM96_EARTH_EQUATORIAL_RADIUS, Constants.EGM96_EARTH_MU,
247                                                           Constants.EGM96_EARTH_C20, 0.0, 0.0, 0.0, 0.0);
248 
249         // Earth and frame
250         double ae =  6378137.0; // equatorial radius in meter
251         double f  =  1.0 / 298.257223563; // flattening
252         Frame itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true); // terrestrial frame at an arbitrary date
253         BodyShape earth = new OneAxisEllipsoid(ae, f, itrf);
254 
255         // Station
256         final double longitude = FastMath.toRadians(-147.5);
257         final double latitude  = FastMath.toRadians(64);
258         final double altitude  = 160;
259         final GeodeticPoint station1 = new GeodeticPoint(latitude, longitude, altitude);
260         final TopocentricFrame sta1Frame = new TopocentricFrame(earth, station1, "station1");
261 
262         // Event definition
263         final double maxcheck  = 120.0;
264         final double elevation = FastMath.toRadians(5.);
265         final double threshold = 10.0;
266         final EventDetector rawEvent = new ElevationDetector(maxcheck, threshold, sta1Frame)
267                                                 .withConstantElevation(elevation)
268                                                 .withHandler(new ContinueOnEvent<ElevationDetector>());
269         final EventsLogger logger = new EventsLogger();
270         kepler.addEventDetector(logger.monitorDetector(rawEvent));
271 
272         // Propagate from the initial date to the first raising or for the fixed duration
273         kepler.propagate(initialDate.shiftedBy(60*60*24.0*40));
274         int countIncreasing = 0;
275         int countDecreasing = 0;
276         for (LoggedEvent le : logger.getLoggedEvents()) {
277             if (le.isIncreasing()) {
278                 ++countIncreasing;
279             } else {
280                 ++countDecreasing;
281             }
282         }
283         Assert.assertEquals(314, countIncreasing);
284         Assert.assertEquals(314, countDecreasing);
285 
286     }
287 
288     @Test
289     public void testIssue110() {
290 
291         // KEPLERIAN PROPAGATOR
292         final Frame eme2000Frame = FramesFactory.getEME2000();
293         final AbsoluteDate initDate = AbsoluteDate.J2000_EPOCH;
294         final double a = 7000000.0;
295         final Orbit initialOrbit = new KeplerianOrbit(a, 0.0,
296                 FastMath.PI / 2.2, 0.0, FastMath.PI / 2., 0.0,
297                 PositionAngle.TRUE, eme2000Frame, initDate,
298                 Constants.EGM96_EARTH_MU);
299         final KeplerianPropagator kProp = new KeplerianPropagator(initialOrbit);
300 
301         // earth shape
302         final OneAxisEllipsoid earthShape = new OneAxisEllipsoid(
303                 Constants.WGS84_EARTH_EQUATORIAL_RADIUS,
304                 Constants.WGS84_EARTH_FLATTENING, FramesFactory.getITRF(IERSConventions.IERS_2010, true));
305         // Ground station
306         final GeodeticPoint stat = new GeodeticPoint(FastMath.toRadians(35.),
307                 FastMath.toRadians(149.8), 0.);
308         final TopocentricFrame station = new TopocentricFrame(earthShape, stat,
309                 "GSTATION");
310 
311         // detector creation
312         // =================
313         final double maxCheck = 600.;
314         final double threshold = 1.0e-3;
315         final EventDetector rawEvent = new ElevationDetector(maxCheck, threshold, station)
316                                                     .withConstantElevation(FastMath.toRadians(5.0))
317                                                     .withHandler(new ContinueOnEvent<ElevationDetector>());
318         final EventsLogger logger = new EventsLogger();
319         kProp.addEventDetector(logger.monitorDetector(rawEvent));
320 
321         // PROPAGATION with DETECTION
322         final AbsoluteDate finalDate = initDate.shiftedBy(30 * 60.);
323 
324         kProp.propagate(finalDate);
325         Assert.assertEquals(2, logger.getLoggedEvents().size());
326         Assert.assertTrue(logger.getLoggedEvents().get(0).isIncreasing());
327         Assert.assertEquals(478.945, logger.getLoggedEvents().get(0).getState().getDate().durationFrom(initDate), 1.0e-3);
328         Assert.assertFalse(logger.getLoggedEvents().get(1).isIncreasing());
329         Assert.assertEquals(665.721, logger.getLoggedEvents().get(1).getState().getDate().durationFrom(initDate), 1.0e-3);
330 
331     }
332 
333 
334     public void testPresTemp() {
335 
336         final TimeScale utc = TimeScalesFactory.getUTC();
337         final Vector3D position = new Vector3D(-6142438.668, 3492467.56, -25767.257);
338         final Vector3D velocity = new Vector3D(505.848, 942.781, 7435.922);
339         final AbsoluteDate date = new AbsoluteDate(2003, 9, 16, utc);
340         final Orbit orbit = new EquinoctialOrbit(new PVCoordinates(position,  velocity),
341                                                  FramesFactory.getEME2000(), date, mu);
342 
343         Propagator propagator =
344             new EcksteinHechlerPropagator(orbit, ae, mu, c20, c30, c40, c50, c60);
345 
346         // Earth and frame
347         double ae =  6378137.0; // equatorial radius in meter
348         double f  =  1.0 / 298.257223563; // flattening
349         Frame itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true); // terrestrial frame at an arbitrary date
350         BodyShape earth = new OneAxisEllipsoid(ae, f, itrf);
351         GeodeticPoint point = new GeodeticPoint(FastMath.toRadians(48.833),
352                                                 FastMath.toRadians(2.333),
353                                                 0.0);
354         TopocentricFrame topo = new TopocentricFrame(earth, point, "Gstation");
355         EarthStandardAtmosphereRefraction refractionModel = new EarthStandardAtmosphereRefraction();
356         ElevationDetector detector = new ElevationDetector(topo)
357                                                  .withRefraction(refractionModel)
358                                                  .withHandler(new StopOnIncreasing<ElevationDetector>());
359         refractionModel.setPressure(101325);
360         refractionModel.setTemperature(290);
361 
362         AbsoluteDate startDate = new AbsoluteDate(2003, 9, 15, 20, 0, 0, utc);
363         propagator.resetInitialState(propagator.propagate(startDate));
364         propagator.addEventDetector(detector);
365         final SpacecraftState fs = propagator.propagate(startDate.shiftedBy(Constants.JULIAN_DAY));
366         double elevation = topo.getElevation(fs.getPVCoordinates().getPosition(), fs.getFrame(), fs.getDate());
367         Assert.assertEquals(FastMath.toRadians(1.7026104902251749), elevation, 2.0e-5);
368 
369     }
370 
371     @Test
372     public void testIssue203() {
373 
374         //  Initial state definition : date, orbit
375         AbsoluteDate initialDate = new AbsoluteDate("2012-01-26T07:00:00.000", TimeScalesFactory.getUTC());
376 
377         Frame inertialFrame = FramesFactory.getEME2000(); // inertial frame for orbit definition
378 
379         Orbit initialOrbit = new KeplerianOrbit(6828137.5, 7.322641060181212E-8, 1.7082667003713938, 0.0, 1.658054062748353, 1.2231496082116026E-4, PositionAngle.TRUE , inertialFrame, initialDate, Constants.WGS84_EARTH_MU);
380 
381         Propagator propagator =
382                 new EcksteinHechlerPropagator(initialOrbit,
383                         Constants.EGM96_EARTH_EQUATORIAL_RADIUS,
384                         Constants.EGM96_EARTH_MU,
385                         Constants.EGM96_EARTH_C20,
386                         Constants.EGM96_EARTH_C30,
387                         Constants.EGM96_EARTH_C40,
388                         Constants.EGM96_EARTH_C50,
389                         Constants.EGM96_EARTH_C60);
390 
391         // Earth and frame
392         Frame earthFrame = FramesFactory.getITRF(IERSConventions.IERS_2010, true);
393         BodyShape earth = new OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS,
394                                                Constants.WGS84_EARTH_FLATTENING,
395                                                earthFrame);
396 
397         // Station
398         final double longitude = FastMath.toRadians(21.0);
399         final double latitude  = FastMath.toRadians(67.9);
400         final double altitude  = 300.0;
401 
402         final GeodeticPoint station1 = new GeodeticPoint(latitude, longitude, altitude);
403         final TopocentricFrame sta1Frame = new TopocentricFrame(earth, station1, "station1");
404 
405         double [][] maskValues = {
406             {-0.017453292519943098, 0.006981317007977318}, {0.0, 0.006981317007977318},
407             {0.017453292519943295, 0.006981317007977318}, {0.03490658503988659, 0.010471975511965976},
408             {0.05235987755982989, 0.012217304763960306}, {0.06981317007977318, 0.010471975511965976},
409             {0.08726646259971647, 0.010471975511965976}, {0.10471975511965978, 0.012217304763960306},
410             {0.12217304763960307, 0.010471975511965976}, {0.13962634015954636, 0.008726646259971648},
411             {0.15707963267948966, 0.008726646259971648}, {0.17453292519943295, 0.006981317007977318},
412             {0.19198621771937624, 0.006981317007977318}, {0.20943951023931956, 0.006981317007977318},
413             {0.22689280275926285, 0.005235987755982988}, {0.24434609527920614, 0.005235987755982988},
414             {0.2617993877991494, 0.003490658503988659}, {0.2792526803190927, 0.003490658503988659},
415             {0.29670597283903605, 0.0017453292519943296}, {0.3141592653589793, 0.003490658503988659},
416             {0.33161255787892263, 0.0017453292519943296}, {0.3490658503988659, 0.0},
417             {0.3665191429188092, 0.012217304763960306}, {0.3839724354387525, 0.012217304763960306},
418             {0.4014257279586958, 0.0}, {0.4188790204786391, 0.010471975511965976},
419             {0.4363323129985824, 0.029670597283903602}, {0.4537856055185257, 0.029670597283903602},
420             {0.47123889803846897, 0.017453292519943295}, {0.4886921905584123, 0.0},
421             {0.5061454830783556, 0.029670597283903602}, {0.5235987755982988, 0.015707963267948967},
422             {0.5410520681182421, 0.005235987755982988}, {0.5585053606381855, 0.024434609527920613},
423             {0.5759586531581288, 0.041887902047863905}, {0.5934119456780721, 0.06283185307179587},
424             {0.6108652381980153, 0.05235987755982989}, {0.6283185307179586, 0.05759586531581287},
425             {0.6457718232379019, 0.061086523819801536}, {0.6632251157578453, 0.05759586531581287},
426             {0.6806784082777885, 0.04363323129985824}, {0.6981317007977318, 0.059341194567807204},
427             {0.7155849933176751, 0.07504915783575616}, {0.7330382858376184, 0.08726646259971647},
428             {0.7504915783575618, 0.08726646259971647}, {0.767944870877505, 0.07330382858376185},
429             {0.7853981633974483, 0.07853981633974483}, {0.8028514559173916, 0.09075712110370514},
430             {0.8203047484373349, 0.0942477796076938}, {0.8377580409572782, 0.11519173063162574},
431             {0.8552113334772214, 0.11519173063162574}, {0.8726646259971648, 0.12566370614359174},
432             {0.8901179185171081, 0.12566370614359174}, {0.9075712110370514, 0.10122909661567112},
433             {0.9250245035569946, 0.11868238913561441}, {0.9424777960769379, 0.11868238913561441},
434             {0.9599310885968813, 0.11868238913561441}, {0.9773843811168246, 0.10821041362364843},
435             {0.9948376736367679, 0.12217304763960307}, {1.0122909661567112, 0.12740903539558607},
436             {1.0297442586766545, 0.11344640137963143}, {1.0471975511965976, 0.11344640137963143},
437             {1.064650843716541, 0.06632251157578452}, {1.0821041362364843, 0.12391837689159739},
438             {1.0995574287564276, 0.12391837689159739}, {1.117010721276371, 0.10995574287564276},
439             {1.1344640137963142, 0.09250245035569947}, {1.1519173063162575, 0.12740903539558607},
440             {1.1693705988362009, 0.1308996938995747}, {1.1868238913561442, 0.1117010721276371},
441             {1.2042771838760873, 0.1117010721276371}, {1.2217304763960306, 0.0942477796076938},
442             {1.239183768915974, 0.10821041362364843}, {1.2566370614359172, 0.09599310885968812},
443             {1.2740903539558606, 0.09948376736367678}, {1.2915436464758039, 0.09773843811168245},
444             {1.3089969389957472, 0.08726646259971647}, {1.3264502315156905, 0.09250245035569947},
445             {1.3439035240356338, 0.10122909661567112}, {1.361356816555577, 0.09250245035569947},
446             {1.3788101090755203, 0.08552113334772216}, {1.3962634015954636, 0.08726646259971647},
447             {1.413716694115407, 0.08028514559173916}, {1.4311699866353502, 0.05759586531581287},
448             {1.4486232791552935, 0.054105206811824215}, {1.4660765716752369, 0.06632251157578452},
449             {1.4835298641951802, 0.08028514559173916}, {1.5009831567151235, 0.061086523819801536},
450             {1.5184364492350666, 0.048869219055841226}, {1.53588974175501, 0.0715584993317675},
451             {1.5533430342749532, 0.07504915783575616}, {1.5707963267948966, 0.05235987755982989},
452             {1.5882496193148399, 0.05235987755982989}, {1.6057029118347832, 0.06981317007977318},
453             {1.6231562043547265, 0.054105206811824215}, {1.6406094968746698, 0.0645771823237902},
454             {1.6580627893946132, 0.059341194567807204}, {1.6755160819145565, 0.029670597283903602},
455             {1.6929693744344996, 0.03316125578789226}, {1.710422666954443, 0.059341194567807204},
456             {1.7278759594743862, 0.0645771823237902}, {1.7453292519943295, 0.06283185307179587},
457             {1.7627825445142729, 0.061086523819801536}, {1.7802358370342162, 0.06806784082777885},
458             {1.7976891295541595, 0.06632251157578452}, {1.8151424220741028, 0.059341194567807204},
459             {1.8325957145940461, 0.05759586531581287}, {1.8500490071139892, 0.05759586531581287},
460             {1.8675022996339325, 0.0471238898038469}, {1.8849555921538759, 0.059341194567807204},
461             {1.9024088846738192, 0.05061454830783556}, {1.9198621771937625, 0.05061454830783556},
462             {1.9373154697137058, 0.024434609527920613}, {1.9547687622336491, 0.027925268031909273},
463             {1.9722220547535925, 0.041887902047863905}, {1.9896753472735358, 0.024434609527920613},
464             {2.007128639793479, 0.029670597283903602}, {2.0245819323134224, 0.03316125578789226},
465             {2.0420352248333655, 0.03665191429188092}, {2.059488517353309, 0.04537856055185257},
466             {2.076941809873252, 0.041887902047863905}, {2.0943951023931953, 0.05759586531581287},
467             {2.111848394913139, 0.06283185307179587}, {2.129301687433082, 0.06806784082777885},
468             {2.1467549799530254, 0.05759586531581287}, {2.1642082724729685, 0.059341194567807204},
469             {2.181661564992912, 0.06806784082777885}, {2.199114857512855, 0.06283185307179587},
470             {2.2165681500327987, 0.054105206811824215}, {2.234021442552742, 0.05235987755982989},
471             {2.251474735072685, 0.059341194567807204}, {2.2689280275926285, 0.07330382858376185},
472             {2.2863813201125716, 0.06283185307179587}, {2.303834612632515, 0.05235987755982989},
473             {2.321287905152458, 0.061086523819801536}, {2.3387411976724017, 0.048869219055841226},
474             {2.356194490192345, 0.06632251157578452}, {2.3736477827122884, 0.05061454830783556},
475             {2.3911010752322315, 0.07679448708775051}, {2.4085543677521746, 0.06283185307179587},
476             {2.426007660272118, 0.05585053606381855}, {2.443460952792061, 0.061086523819801536},
477             {2.4609142453120048, 0.06806784082777885}, {2.478367537831948, 0.0645771823237902},
478             {2.4958208303518914, 0.06283185307179587}, {2.5132741228718345, 0.06283185307179587},
479             {2.530727415391778, 0.0645771823237902}, {2.548180707911721, 0.07504915783575616},
480             {2.5656340004316642, 0.0715584993317675}, {2.5830872929516078, 0.0645771823237902},
481             {2.600540585471551, 0.059341194567807204}, {2.6179938779914944, 0.06283185307179587},
482             {2.6354471705114375, 0.06632251157578452}, {2.652900463031381, 0.06283185307179587},
483             {2.670353755551324, 0.06632251157578452}, {2.6878070480712677, 0.0645771823237902}};
484         ElevationMask mask = new ElevationMask(maskValues);
485 
486 
487         final AbsoluteDate start = new AbsoluteDate("2012-02-10T22:00:00.000", TimeScalesFactory.getUTC());
488         final AbsoluteDate end   = initialDate.shiftedBy(1000 * Constants.JULIAN_DAY);
489 
490         // Event definition
491         final double maxcheck  = 60.0;
492         final double threshold =  2.0; // 0.001;
493         final EventDetector sta1Visi =
494                 new ElevationDetector(maxcheck, threshold, sta1Frame).
495                 withElevationMask(mask).
496                 withHandler(new EventHandler<ElevationDetector>() {
497 
498                     private int count = 6;
499                     @Override
500                     public Action eventOccurred(SpacecraftState s, ElevationDetector detector, boolean increasing) {
501                         return (--count > 0) ? Action.CONTINUE : Action.STOP;
502                     }
503 
504                 });
505 
506         // Add event to be detected
507         EventsLogger logger = new EventsLogger();
508         propagator.addEventDetector(logger.monitorDetector(sta1Visi));
509 
510         // Propagate until the sixth event
511         propagator.propagate(start, end);
512 
513         List<LoggedEvent> events = logger.getLoggedEvents();
514         Assert.assertEquals(6, events.size());
515 
516         // despite the events 2 and 3 are closer to each other than the convergence threshold
517         // the second one is not merged into the first one
518         AbsoluteDate d2 = events.get(2).getState().getDate();
519         AbsoluteDate d3 = events.get(3).getState().getDate();
520         Assert.assertEquals(1.529, d3.durationFrom(d2), 0.01);
521 
522     }
523 
524     @Before
525     public void setUp() {
526         Utils.setDataRoot("regular-data");
527         mu  = 3.9860047e14;
528         ae  = 6.378137e6;
529         c20 = -1.08263e-3;
530         c30 = 2.54e-6;
531         c40 = 1.62e-6;
532         c50 = 2.3e-7;
533         c60 = -5.5e-7;
534     }
535 
536     @After
537     public void tearDown() {
538         mu   = Double.NaN;
539         ae   = Double.NaN;
540         c20  = Double.NaN;
541         c30  = Double.NaN;
542         c40  = Double.NaN;
543         c50  = Double.NaN;
544         c60  = Double.NaN;
545     }
546 
547 }
548