Brief Guide to Doing SPICE Hands-On Lessons Using WGC |
Table of ContentsBrief Guide to Doing SPICE Hands-On Lessons Using WGC Overview WGC and WGC Tutorial URLs ``CASSINI Remote Sensing'' Hands-On Lesson Using WGC Kernels Used Time Conversion (convtm) Obtaining Target States and Positions (getsta) Spacecraft Orientation and Reference Frames (xform) Computing Sub-spacecraft and Sub-solar Points (subpts) Intersecting Vectors with a Triaxial Ellipsoid (fovint) ``ExoMars 2016 Remote Sensing'' Hands-On Lesson Using WGC Kernels Used Time Conversion (convtm) Time Conversion -- Selected Extra Credit Obtaining Target States and Positions (getsta) Obtaining Target States and Positions -- Selected Extra Credit Spacecraft Orientation and Reference Frames (xform) Spacecraft Orientation and Reference Frames -- Selected Extra Credit Computing Sub-spacecraft and Sub-solar Points (subpts) Computing Sub-spacecraft and Sub-solar Points -- Selected Extra Credit Intersecting Vectors with a Triaxial Ellipsoid (fovint) ``In-situ Sensing'' Hands-On Lesson Using WGC Kernels Used Step-1: ``UTC to ET'' Step-2: ``SCLK to ET'' Step-3: ``Spacecraft State'' Step-4: ``Sun Direction'' Step-5: ``Sub-Spacecraft Point'' Step-6: ``Spacecraft Velocity'' ``Mars Express Geometric Event Finding'' Hands-On Lesson Using WGC Kernels Used Find View Periods Find Times when Target is Visible ``ExoMars-16 TGO Geometric Event Finding'' Hands-On Lesson Using WGC Kernels Used Find View Periods Find Times when Target is Visible Extra Credit ``Binary PCK'' Hands-On Lesson Using WGC Moon rotation (mrotat) Earth rotation (erotat) Brief Guide to Doing SPICE Hands-On Lessons Using WGC
Overview
Instructions for each lesson are provided in a separate section below. They follow the lesson steps and individual assignments within each step, indicate which WGC computation panels (``calculations'') should be used and what inputs should be entered or selected in these calculations, and what key outputs should be expected from WGC. Where applicable, they indicate that a particular quantity computed in the lesson cannot be computed by WGC. WGC and WGC Tutorial URLs
http://spice.esac.esa.int/webgeocalc/#NewCalculationWGC at NAIF can be accessed at:
http://wgc.jpl.nasa.gov:8080/webgeocalc/#NewCalculationThe WGC tutorial and examples are provided at:
http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/Tutorials/ pdf/individual_docs/36_webgeocalc.pdf http://naif.jpl.nasa.gov/naif/wgc_easy_usage_example.pdf http://naif.jpl.nasa.gov/naif/wgc_challenging_usage_example.pdf ``CASSINI Remote Sensing'' Hands-On Lesson Using WGCKernels Used
Time Conversion (convtm)
Time system UTC Time format Calendar date and time Input time 2004 jun 11 19:32:00 Output time system TDB Output time format Seconds past J2000WGC will return the following ET seconds past J2000:
140254384.184620To compute calendar ET in the default format, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system UTC Time format Calendar date and time Input time 2004 jun 11 19:32:00 Output time system TDBWGC will return the following calendar ET time string:
2004-06-11 19:33:04.184625 TDBTo compute calendar ET in a custom format, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system UTC Time format Calendar date and time Input time 2004 jun 11 19:32:00 Output time system TDB Custom format YYYY-MON-DDTHR:MN:SC ::TDBWGC will return the following calendar ET time string:
2004-JUN-11T19:33:04To compute spacecraft clock time, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system UTC Time format Calendar date and time Input time 2004 jun 11 19:32:00 Output time system Spacecraft clock (SCLK=-82)WGC will return the following SCLK time string:
1/1465674964.105 Obtaining Target States and Positions (getsta)
Target PHOEBE Observer CASSINI Reference frame J2000 Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 State representation RectangularWGC will return the following state vector, km and km/s:
-119.92092897 2194.13933986 -57.63897986 -5.98023114 -2.11880531 -0.29482213To compute the apparent position of Earth as seen from CASSINI in the J2000 frame and one way light time between CASSINI and the apparent position of Earth, specify/select the following inputs in the ``State Vector'' calculation:
Target EARTH Observer CASSINI Reference frame J2000 Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 State representation RectangularWGC will return the following position vector, km, and one way light time, s:
353019393.12261910 -1328180352.14030500 -568134171.69730540 4960.42691203To compute the apparent position of Sun as seen from Phoebe in the J2000 frame, specify/select the following inputs in the ``State Vector'' calculation:
Target SUN Observer PHOEBE Reference frame J2000 Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 State representation RectangularWGC will return the following position vector, km:
376551465.27159620 -1190495630.30282120 -508438699.11000470Note that WGC will also compute the distance between Sun and Phoebe body centers, km:
1348176829.09957000but it cannot convert this distance to AUs. Spacecraft Orientation and Reference Frames (xform)
Target PHOEBE Observer CASSINI Reference frame IAU_PHOEBE Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 State representation RectangularWGC will return the following state vector, km and km/s:
-1982.63976162 -934.53047112 -166.56259513 3.97083213 -3.81249566 -2.37166299WGC does not have a separate calculation to compute angles between directions to objects and instrument boresights or axes of a reference frame, making such computations not possible in general. But for cases when the axis is ``Z'' such computations can be done using the ``State Vector'' calculation with the ``Spherical Coordinates'' output, in which the colatitude is equal to the desired angle. To compute the angular separation between the apparent position of Earth and the CASSINI high gain antenna boresight, specify/select the following inputs in the ``State Vector'' calculation:
Target EARTH Observer CASSINI Reference frame CASSINI_HGA Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 State representation SphericalWGC will return the following output colatitude, deg:
71.92414848 Computing Sub-spacecraft and Sub-solar Points (subpts)
Target PHOEBE Reference frame IAU_PHOEBE Observer CASSINI Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
104.49789074 45.26884577 7.38331473Note that WCG will compute the altitude but it will be labeled ``Observer Distance (km)'' in the output table and will have the following distance, km:
2084.11604205To compute the apparent sub-solar point on Phoebe as seen from CASSINI in the IAU_PHOEBE frame , specify/select the following inputs in the ``Sub-Solar Point'' calculation:
Calculation type Sub-Solar Point Target PHOEBE Reference frame IAU_PHOEBE Observer CASSINI Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
78.68071625 76.87865160 -21.88456729 Intersecting Vectors with a Triaxial Ellipsoid (fovint)
Target PHOEBE Reference frame IAU_PHOEBE Observer CASSINI Ray vector CASSINI_ISS_NAC field-of-view boundary vectors Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vectors, km:
91.02635667 67.19017758 2.03016242 91.02635667 67.19017758 2.03016242 91.02635667 67.19017758 2.03016242 91.02635667 67.19017758 2.03016242To compute the planetocentric longitudes and latitudes of the FOV boundary vector surface intercept points in the IAU_PHOEBE frame, specify/select the following inputs in the ``Surface Intercept Point'' calculation:
Target PHOEBE Reference frame IAU_PHOEBE Observer CASSINI Ray vector CASSINI_ISS_NAC field-of-view boundary vectors Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 Position representation PlanetocentricWGC will return the following longitudes and latitudes, deg:
36.43251123 1.02800787 36.55583078 7.49186596 43.42988023 7.37325329 43.23917363 0.86454948Both computations above also returned the illumination angles the FOV boundary vector surface intercept points but these angles were omitted from the output shown above. To compute the Cartesian position vectors of the FOV boresight surface intercept point in the IAU_PHOEBE frame, specify/select the following inputs in the ``Surface Intercept Point'' calculation:
Target PHOEBE Reference frame IAU_PHOEBE Observer CASSINI Ray vector CASSINI_ISS_NAC boresight Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
86.39001297 72.08919557 8.25459687To compute the planetocentric longitude and latitude of the FOV boresight surface intercept point in the IAU_PHOEBE frame and the illumination angles at this point, specify/select the following inputs in the ``Surface Intercept Point'' calculation:
Target PHOEBE Reference frame IAU_PHOEBE Observer CASSINI Ray vector CASSINI_ISS_NAC boresight Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2004 JUN 11 19:32:00 Position representation PlanetocentricWGC will return the following longitude and latitude, deg:
39.84371945 4.19587780and the following incidence, emission, and phase angles, deg:
18.24722120 17.85830930 28.13948173WGC cannot compute the local solar time at the boresight intercept point. ``ExoMars 2016 Remote Sensing'' Hands-On Lesson Using WGCKernels Used
Time Conversion (convtm)
Time system UTC Time format Calendar date and time Input time 2018 jun 11 19:32:00 Output time system TDB Output time format Seconds past J2000WGC will return the following ET seconds past J2000:
582017589.184640To compute calendar ET in the default format, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system UTC Time format Calendar date and time Input time 2018 jun 11 19:32:00 Output time system TDB Output time format Calendar (year-month-day)WGC will return the following calendar ET time string:
2018-06-11 19:33:09.184642To compute calendar ET in a custom format, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system UTC Time format Calendar date and time Input time 2018 jun 11 19:32:00 Output time system TDB Custom format YYYY-MON-DDTHR:MN:SC ::TDBWGC will return the following calendar ET time string:
2018-JUN-11T19:33:09To compute spacecraft clock time, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system UTC Time format Calendar date and time Input time 2018 jun 11 19:32:00 Output time system Spacecraft clock (SCLK=-143) Output time format Spacecraft clock stringWGC will return the following SCLK time string:
1/0070841719.26698 Time Conversion -- Selected Extra Credit
Time system UTC Time format Calendar date and time Input time 2018 jun 11 19:32:00 Output time system TDB Output time format Julian DateWGC will return the following SCLK time string:
2458281.314689600 JD TDB5. To compute the earliest UTC time that can be converted to ExoMars-16 TGO spacecraft clock, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system Spacecraft clock (SCLK=-143) Time format Spacecraft clock string Input time 0.0 Output time system UTC Output time format Calendar (year-month-day)WGC will return the following UTC time string:
2016-03-13 21:34:13.193650 UTC6. To compute the spacecraft clock time obtained in the regular task back to UTC Time and present it in ISO calendar date format, with a resolution of milliseconds, specify/select the following inputs in the ``Time Conversion'' calculation:
Time system Spacecraft clock (SCLK=-143) Time format Spacecraft clock string Input time 1/0070841719.26698 Output time system UTC Custom format YYYY-MM-DDTHR:MN:SC.### ::RNDWGC will return the following UTC time string:
2018-06-11T19:32:00.000 Obtaining Target States and Positions (getsta)
Target MARS Observer EXOMARS 2016 TGO Reference frame J2000 Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 State representation RectangularWGC will return the following state vector, km and km/s:
2911.82242547 -2033.80245966 -1291.70085522 1.30950490 -0.05597018 3.10432898To compute the apparent position of Earth as seen from TGO in the J2000 frame and one way light time between TGO and the apparent position of Earth, specify/select the following inputs in the ``State Vector'' calculation:
Target EARTH Observer EXOMARS 2016 TGO Reference frame J2000 Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 State representation RectangularWGC will return the following position vector, km, and one way light time, s:
-49609884.08045448 57070665.86178913 30304236.92973865 271.73803215To compute the apparent position of Sun as seen from Mars in the J2000 frame, specify/select the following inputs in the ``State Vector'' calculation:
Target SUN Observer MARS Reference frame J2000 Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 State representation RectangularWGC will return the following position vector, km:
-24712734.28893231 194560532.94319060 89906636.78934350Note that WGC will also compute the distance between Sun and Mars body centers, km:
215749214.49206870but it cannot convert this distance to AUs. Obtaining Target States and Positions -- Selected Extra Credit
Target SUN Observer MARS Reference frame J2000 Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 State representation Rectangularand these corrections for NONE (the geometric position), LT (the reception light time only corrected position), and LT+S (the apparent position):
Light propagation No correction Light propagation To observer Light-time algorithm Newtonian Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberrationWGC will return the following position vectors, km, correspondingly:
-24730875.20069792 194558449.55971023 89906170.85450794 -24730866.48857886 194558445.24649155 89906168.75352160 -24712734.28893231 194560532.94319060 89906636.78934350 Spacecraft Orientation and Reference Frames (xform)
Target MARS Observer EXOMARS 2016 TGO Reference frame IAU_MARS Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 State representation RectangularWGC will return the following state vector, km and km/s:
-2843.46412456 2235.45954373 1095.89496870 0.31144328 -1.15192925 3.08212262WGC does not have a separate calculation to compute angles between directions to objects and instrument boresights or axes of a reference frame, making such computations not possible in general. But for cases when the axis is ``Z'' such computations can be done using the ``State Vector'' calculation with the ``Spherical Coordinates'' output, in which the colatitude is equal to the desired angle. Since the nominal instrument view direction is the ``-Y'' axis of the ``TGO_SPACECRAFT'' frame we cannot use this approach with this frame but we can use it with the ``TGO_NOMAD_LNO_NAD'' frame which has its ``Z'' axis along the view direction. To compute the angular separation between the apparent position of Mars and the TGO nominal instrument view direction, specify/select the following inputs in the ``State Vector'' calculation:
Target MARS Observer EXOMARS 2016 TGO Reference frame TGO_NOMAD_LNO_NAD Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 State representation SphericalWGC will return the following output colatitude, deg:
5.43847143 Spacecraft Orientation and Reference Frames -- Selected Extra Credit
Target SUN Observer EXOMARS 2016 TGO Reference frame TGO_NOMAD_LNO_NAD Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 State representation SphericalWGC will return the following output colatitude, deg:
130.54279733This angle is greater than 90 degrees so the science deck is not illuminated. Computing Sub-spacecraft and Sub-solar Points (subpts)
Target MARS Reference frame IAU_MARS Observer EXOMARS 2016 TGO Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
2554.16465516 -2008.01038262 -983.24042077Note that WCG will compute the altitude but it will be labeled ``Observer Distance (km)'' in the output table and will have the following distance, km:
385.04529279To compute the apparent sub-solar point on Mars as seen from TGO in the IAU_MARS frame using the ``Near point: ellipsoid'' method, specify/select the following inputs in the ``Sub-Solar Point'' calculation:
Calculation type Sub-Solar Point Target MARS Reference frame IAU_MARS Observer EXOMARS 2016 TGO Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
487.58869797 -3348.61049793 -286.69722014 Computing Sub-spacecraft and Sub-solar Points -- Selected Extra Credit
Calculation type Sub-Solar Point Target MARS Reference frame IAU_MARS Observer EXOMARS 2016 TGO Sub-point type Intercept point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
487.54669671 -3348.32205372 -290.077215112. To compute the apparent sub-observer point of TGO on Phobos in the IAU_PHOBOS frame, specify/select the following inputs in the ``Sub-Observer Point'' calculation:
Target PHOBOS Reference frame IAU_PHOBOS Observer EXOMARS 2016 TGO Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
12.05913904 4.17308831 -0.675466163. To compute the planetocentric coordinates of the apparent sub-observer point of TGO on Phobos in the IAU_PHOBOS frame, specify/select the following inputs in the ``Sub-Observer Point'' calculation:
Target PHOBOS Reference frame IAU_PHOBOS Observer EXOMARS 2016 TGO Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation PlanetocentricWGC will return the following latitude and longitude, deg, and radius, km:
-3.03000878 19.08827715 12.77864449WGC does not allow computing planetodetic and planetographic coordinates on bodies that are tri-axial ellipsoids with different equatorial radii. Choosing the planetographic coordinates for output will result in the following error message:
Reference frame center is not a spheroid. Planetodetic and planetographic coordinate representations can only be calculated for bodies with equal equatorial axes. The center body of the reference frame, PHOBOS, has equatorial axes that differ, 13.0 and 11.4. Use planetocentric coordinates instead. Intersecting Vectors with a Triaxial Ellipsoid (fovint)
Target MARS Reference frame IAU_MARS Observer EXOMARS 2016 TGO Ray vector TGO_NOMAD_LNO_NAD field-of-view boundary vectors Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vectors, km:
91.02635667 67.19017758 2.03016242 91.02635667 67.19017758 2.03016242 91.02635667 67.19017758 2.03016242 91.02635667 67.19017758 2.03016242To compute the planetocentric longitudes and latitudes of the FOV boundary vector surface intercept points in the IAU_MARS frame, specify/select the following inputs in the ``Surface Intercept Point'' calculation:
Target MARS Reference frame IAU_MARS Observer EXOMARS 2016 TGO Ray vector TGO_NOMAD_LNO_NAD field-of-view boundary vectors Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation PlanetocentricWGC will return the following longitudes and latitudes, deg:
36.43251123 1.02800787 36.55583078 7.49186596 43.42988023 7.37325329 43.23917363 0.86454948Both computations above also returned the illumination angles the FOV boundary vector surface intercept points but these angles were omitted from the output shown above. To compute the Cartesian position vectors of the FOV boresight surface intercept point in the IAU_MARS frame, specify/select the following inputs in the ``Surface Intercept Point'' calculation:
Target MARS Reference frame IAU_MARS Observer EXOMARS 2016 TGO Ray vector TGO_NOMAD_LNO_NAD boresight Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation RectangularWGC will return the following position vector, km:
86.39001297 72.08919557 8.25459687To compute the planetocentric longitude and latitude of the FOV boresight surface intercept point in the IAU_MARS frame and the illumination angles at this point, specify/select the following inputs in the ``Surface Intercept Point'' calculation:
Target MARS Reference frame IAU_MARS Observer EXOMARS 2016 TGO Ray vector TGO_NOMAD_LNO_NAD boresight Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2018 JUN 11 19:32:00 Position representation PlanetocentricWGC will return the following longitude and latitude, deg:
39.84371945 4.19587780and the following incidence, emission, and phase angles, deg:
18.24722120 17.85830930 28.13948173WGC cannot compute the local solar time at the boresight intercept point. ``In-situ Sensing'' Hands-On Lesson Using WGCKernels Used
Step-1: ``UTC to ET''
Time system UTC Time format Calendar date and time Input time 2004-06-11T19:32:00 Output time system TDB Output time format Seconds past J2000WGC will return the following ET seconds past J2000:
140254384.184620 Step-2: ``SCLK to ET''
Time system Spacecraft clock (SCLK=-82) Time format Spacecraft clock string Input time 1465674964.105 Output time system TDB Output time format Seconds past J2000WGC will return the following ET seconds past J2000:
140254384.183430Either the input SCLK time or these output ET seconds past J2000 should be used as the input time in all remaining ``In-situ Sensing'' lesson steps in order for WGC to compute values matching the results provided in the programming lesson. The output ET seconds may be saved for future use in the WGC ``Saved Values'' area by simply clicking on them with the left mouse button. The saved value can then be drag-n-dropped from the ``Saved Values'' area into the empty ``Time:'' box in the next calculation. Step-3: ``Spacecraft State''
Target CASSINI Observer SUN Reference frame ECLIPJ2000 Light propagation No correction Time system TDB Time format Seconds past J2000 Input time 140254384.183430 State representation RectangularWGC will return the following state vector, km and km/s:
-376599061.91656125 1294487780.92915730 -7064853.05469811 -5.16422619 0.80171891 0.04060306 Step-4: ``Sun Direction''
Target SUN Observer CASSINI Reference frame CASSINI_INMS Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system TDB Time format Seconds past J2000 Input time 140254384.183430 State representation RectangularWGC will return the following position vector, km:
-391245772.45811266 1188593024.20844320 501745827.05297270 Step-5: ``Sub-Spacecraft Point''
Target PHOEBE Reference frame IAU_PHOEBE Observer CASSINI Sub-point type Near point on ellipsoid Light propagation No correction Time system TDB Time format Seconds past J2000 Input time 140254384.183430 Position representation PlanetocentricWGC will return the following longitude and latitude, deg:
23.42315899 3.70979740WGC cannot compute the direction from the CASSINI spacecraft to the sub-spacecraft point in the INMS frame. Step-6: ``Spacecraft Velocity''
``Mars Express Geometric Event Finding'' Hands-On Lesson Using WGCKernels Used
Find View Periods
Target MEX Observer DSS-14 Reference frame DSS-14_TOPO Light propagation To observer Light-time algorithm Converged Newtonian Stellar aberration Corrected for stellar aberration Time system TDB Time format Calendar date and time Time range 2004 MAY 2 to 2004 MAY 6, step 300 seconds Coordinate condition Latitude is greater than 6 Output time unit hours Complement result window no Result interval adjustment No adjustment Result interval filtering No filteringWGC will return the following interval start and stop times:
2004-05-02 00:00:00.000000 TDB 2004-05-02 05:35:03.096376 TDB 2004-05-02 16:09:14.078641 TDB 2004-05-03 05:33:57.257816 TDB 2004-05-03 16:08:02.279561 TDB 2004-05-04 05:32:50.765340 TDB 2004-05-04 16:06:51.259358 TDB 2004-05-05 05:31:43.600189 TDB 2004-05-05 16:05:40.994061 TDB 2004-05-06 00:00:00.000000 TDBMake sure to save these output intervals in the WGC ``Saved Values'' area using the ``Save All Intervals'' button to make them available for use as input to the next step of the lesson. Find Times when Target is Visible
Calculation type Occultation Event Finder Occultation type Any Front body MARS Front body shape Ellipsoid Front body frame IAU_MARS Back body MEX Back body shape Point Back body frame Observer DSS-14 Light propagation To observer Light-time algorithm Converged Newtonian Time system TDB Time format Calendar date and time Output time unit hours Complement result window yes Result interval adjustment No adjustment Result interval filtering No filteringTo use the time intervals found by the previous step as the input to this calculation, select ``List of Intervals'' in the ``Input times:'' selector and drag and drop saved intervals from the ``Saved Values'' area into the empty ``List of intervals:'' box. WGC will return the following interval start and stop times:
2004-05-02 00:00:00.000000 TDB 2004-05-02 04:49:30.827635 TDB 2004-05-02 16:09:14.078641 TDB 2004-05-02 20:00:22.514122 TDB 2004-05-02 21:01:38.222068 TDB 2004-05-03 03:35:42.256777 TDB 2004-05-03 04:36:42.484694 TDB 2004-05-03 05:33:57.257816 TDB 2004-05-03 16:08:02.279561 TDB 2004-05-03 18:46:26.013964 TDB 2004-05-03 19:46:54.618795 TDB 2004-05-04 02:21:44.562990 TDB 2004-05-04 03:21:56.347988 TDB 2004-05-04 05:32:50.765340 TDB 2004-05-04 16:06:51.259358 TDB 2004-05-04 17:32:25.809031 TDB 2004-05-04 18:32:05.975318 TDB 2004-05-05 01:07:48.264966 TDB 2004-05-05 02:07:11.601765 TDB 2004-05-05 05:31:43.600189 TDB 2004-05-05 16:05:40.994061 TDB 2004-05-05 16:18:35.560693 TDB 2004-05-05 17:17:27.717224 TDB 2004-05-05 23:54:04.672052 TDB ``ExoMars-16 TGO Geometric Event Finding'' Hands-On Lesson Using WGCKernels Used
Find View Periods
Target EXOMARS 2016 TGO Observer NEW_NORCIA Reference frame NEW_NORCIA_TOPO Light propagation To observer Light-time algorithm Converged Newtonian Stellar aberration Corrected for stellar aberration Time system TDB Time format Calendar date and time Time range 2018 JUN 10 to 2018 JUN 14, step 300 seconds Coordinate condition Latitude is greater than 6 Output time unit hours Complement result window no Result interval adjustment No adjustment Result interval filtering No filteringWGC will return the following interval start and stop times:
2018-06-10 00:00:00.000000 TDB 2018-06-10 02:11:17.355621 TDB 2018-06-10 13:19:58.777464 TDB 2018-06-11 02:08:16.008548 TDB 2018-06-11 13:16:50.542539 TDB 2018-06-12 02:05:12.548825 TDB 2018-06-12 13:13:38.573032 TDB 2018-06-13 02:02:06.618874 TDB 2018-06-13 13:10:23.432464 TDB 2018-06-14 00:00:00.000000 TDBMake sure to save these output intervals in the WGC ``Saved Values'' area using the ``Save All Intervals'' button to make them available for use as input to the next step of the lesson. Find Times when Target is Visible
Calculation type Occultation Event Finder Occultation type Any Front body MARS Front body shape Ellipsoid Front body frame IAU_MARS Back body EXOMARS 2016 TGO Back body shape Point Back body frame Observer NEW_NORCIA Light propagation To observer Light-time algorithm Converged Newtonian Time system TDB Time format Calendar date and time Output time unit hours Complement result window yes Result interval adjustment No adjustment Result interval filtering No filteringTo use the time intervals found by the previous step as the input to this calculation, select ``List of Intervals'' in the ``Input times:'' selector and drag and drop saved intervals from the ``Saved Values'' area into the empty ``List of intervals:'' box. WGC will return the following interval start and stop times:
2018-06-10 00:00:00.000000 TDB 2018-06-10 01:00:30.640614 TDB 2018-06-10 01:41:03.610048 TDB 2018-06-10 02:11:17.355621 TDB 2018-06-10 13:28:28.785788 TDB 2018-06-10 14:45:38.197853 TDB 2018-06-10 15:26:21.981505 TDB 2018-06-10 16:43:32.192863 TDB 2018-06-10 17:24:17.290058 TDB 2018-06-10 18:41:27.535612 TDB 2018-06-10 19:22:13.628023 TDB 2018-06-10 20:39:21.785693 TDB 2018-06-10 21:20:08.856427 TDB 2018-06-10 22:37:12.445420 TDB 2018-06-10 23:18:00.834325 TDB 2018-06-11 00:35:01.034340 TDB 2018-06-11 01:15:50.883961 TDB 2018-06-11 02:08:16.008548 TDB 2018-06-11 13:16:50.542539 TDB 2018-06-11 14:20:09.789544 TDB 2018-06-11 15:01:08.370780 TDB 2018-06-11 16:18:03.385855 TDB 2018-06-11 16:59:03.014503 TDB 2018-06-11 18:15:58.739454 TDB 2018-06-11 18:56:59.199542 TDB 2018-06-11 20:13:54.308303 TDB 2018-06-11 20:54:55.301168 TDB 2018-06-11 22:11:47.045226 TDB 2018-06-11 22:52:48.925002 TDB 2018-06-12 00:09:35.868266 TDB 2018-06-12 00:50:39.046685 TDB 2018-06-12 02:05:12.548825 TDB 2018-06-12 13:13:38.573032 TDB 2018-06-12 13:54:43.524958 TDB 2018-06-12 14:35:54.054008 TDB 2018-06-12 15:52:36.256662 TDB 2018-06-12 16:33:47.502777 TDB 2018-06-12 17:50:30.988537 TDB 2018-06-12 18:31:42.896589 TDB 2018-06-12 19:48:26.827964 TDB 2018-06-12 20:29:39.039169 TDB 2018-06-12 21:46:20.933464 TDB 2018-06-12 22:27:33.596215 TDB 2018-06-12 23:44:11.473471 TDB 2018-06-13 00:25:24.992296 TDB 2018-06-13 01:42:00.777360 TDB 2018-06-13 13:10:23.432464 TDB 2018-06-13 13:29:19.789157 TDB 2018-06-13 14:10:38.985039 TDB 2018-06-13 15:27:11.882834 TDB 2018-06-13 16:08:31.566611 TDB 2018-06-13 17:25:06.068241 TDB 2018-06-13 18:06:26.219824 TDB 2018-06-13 19:23:01.820444 TDB 2018-06-13 20:04:22.175372 TDB 2018-06-13 21:20:57.296111 TDB 2018-06-13 22:02:17.650959 TDB 2018-06-13 23:18:49.624491 TDB Extra Credit
Target EXOMARS 2016 TGO Observer MARS Reference frame IAU_MARS Light propagation No correction Time system TDB Time format Calendar date and time Time range 2018 JUN 10 to 2018 JUN 11, step 300 seconds Coordinate condition Latitude equals 0 Output time unit seconds Complement result window no Result interval adjustment No adjustment Result interval filtering No filteringWGC will return the following times:
2018-06-10 00:14:08.836580 TDB 2018-06-10 01:12:34.582095 TDB 2018-06-10 02:12:00.375370 TDB 2018-06-10 03:10:28.808573 TDB 2018-06-10 04:09:53.955311 TDB 2018-06-10 05:08:23.919392 TDB 2018-06-10 06:07:48.630669 TDB 2018-06-10 07:06:17.539430 TDB 2018-06-10 08:05:42.659963 TDB 2018-06-10 09:04:09.120521 TDB 2018-06-10 10:03:34.270188 TDB 2018-06-10 11:01:59.269625 TDB 2018-06-10 12:01:22.866520 TDB 2018-06-10 12:59:49.352117 TDB 2018-06-10 13:59:13.289772 TDB 2018-06-10 14:57:41.242004 TDB 2018-06-10 15:57:07.576976 TDB 2018-06-10 16:55:35.266038 TDB 2018-06-10 17:55:02.773235 TDB 2018-06-10 18:53:30.271499 TDB 2018-06-10 19:52:56.383285 TDB 2018-06-10 20:51:23.966229 TDB 2018-06-10 21:50:47.729319 TDB 2018-06-10 22:49:14.385397 TDB 2018-06-10 23:48:37.583974 TDB2. To find times when ExoMars-16 TGO (TGO) is at periapsis, specify/select the following inputs in the ``Distance Event Finder'' calculation:
Target EXOMARS 2016 TGO Observer MARS Light propagation No correction Time system TDB Time format Calendar date and time Time range 2018 JUN 10 to 2018 JUN 11, step 300 seconds Coordinate condition is local minimum Output time unit seconds Complement result window no Result interval adjustment No adjustment Result interval filtering No filteringWGC will return the following times:
2018-06-10 00:43:06.357819 TDB 2018-06-10 02:40:47.168872 TDB 2018-06-10 04:38:45.496250 TDB 2018-06-10 06:36:32.706773 TDB 2018-06-10 08:34:10.548681 TDB 2018-06-10 10:31:49.108636 TDB 2018-06-10 12:29:20.342207 TDB 2018-06-10 14:27:07.089996 TDB 2018-06-10 16:25:36.081463 TDB 2018-06-10 18:24:02.653942 TDB 2018-06-10 20:22:23.184793 TDB 2018-06-10 22:20:12.453735 TDB3. To find times when ExoMars-16 TGO (TGO) is at apoapsis, specify/select the following inputs in the ``Distance Event Finder'' calculation:
Target EXOMARS 2016 TGO Observer MARS Light propagation No correction Time system TDB Time format Calendar date and time Time range 2018 JUN 10 to 2018 JUN 11, step 300 seconds Coordinate condition is local maximum Output time unit seconds Complement result window no Result interval adjustment No adjustment Result interval filtering No filteringWGC will return the following times:
2018-06-10 01:41:44.632145 TDB 2018-06-10 03:39:31.106999 TDB 2018-06-10 05:37:22.115251 TDB 2018-06-10 07:34:59.674318 TDB 2018-06-10 09:32:25.708394 TDB 2018-06-10 11:29:47.945538 TDB 2018-06-10 13:27:30.200636 TDB 2018-06-10 15:26:02.524463 TDB 2018-06-10 17:24:37.842993 TDB 2018-06-10 19:23:11.265220 TDB 2018-06-10 21:21:13.530306 TDB 2018-06-10 23:18:56.796575 TDB ``Binary PCK'' Hands-On Lesson Using WGCMoon rotation (mrotat)
To compute the Moon-Earth direction using the low accuracy PCK and the IAU_MOON frame, specify/select the following inputs in the ``State Vector'' calculation:
Target EARTH Observer MOON Reference frame IAU_MOON Light propagation To observer Light-time algorithm Converged Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 State representation PlanetocentricWGC will return the following longitude and latitude, deg:
3.61310222 -6.43834182To compute the Moon-Earth direction using a high accuracy PCK and the MOON_ME frame, specify/select the following inputs in the ``State Vector'' calculation:
Target EARTH Observer MOON Reference frame MOON_ME Light propagation To observer Light-time algorithm Converged Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 State representation PlanetocentricWGC will return the following longitude and latitude, deg:
3.61122841 -6.43950148WGC cannot compute angular separation between the Moon-Earth direction vectors in the IAU_MOON and MOON_ME frames. To compute the Moon-Earth direction using a high accuracy PCK and the MOON_PA frame, specify/select the following inputs in the ``State Vector'' calculation:
Target EARTH Observer MOON Reference frame MOON_PA Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 State representation PlanetocentricWGC will return the following longitude and latitude, deg:
3.59331861 -6.41758189WGC cannot compute angular separation between the Moon-Earth direction vectors in the MOON_ME and MOON_PA frames. To compute the sub-Earth point on the Moon using a high accuracy PCK and the MOON_ME frame, specify/select the following inputs in the ``Sub-Observer Point'' calculation:
Target MOON Reference frame MOON_ME Observer EARTH Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Converged Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 Position representation PlanetocentricWGC will return the following longitude and latitude, deg:
3.61141894 -6.43950142To compute the sub-Earth point on the Moon using a high accuracy PCK and the MOON_PA frame, specify/select the following inputs in the ``Sub-Observer Point'' calculation:
Target MOON Reference frame MOON_PA Observer EARTH Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Converged Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 Position representation PlanetocentricWGC will return the following longitude and latitude, deg:
3.59350886 -6.41758182WGC cannot compute the distance between the sub-Earth points computed in the MOON_ME and MOON_PA frames. Earth rotation (erotat)
To compute the Earth-Moon direction using a low accuracy PCK and the IAU_EARTH frame, specify/select the following inputs in the ``State Vector'' calculation:
Target MOON Observer EARTH Reference frame IAU_EARTH Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 State representation PlanetocentricWGC will return the following longitude and latitude, deg:
-35.49627162 26.41695855To compute the Earth-Moon direction using a high accuracy PCK and the ITRF93 frame, specify/select the following inputs in the ``State Vector'' calculation:
Target MOON Observer EARTH Reference frame ITRF93 Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 State representation PlanetocentricWGC will return the following longitude and latitude, deg:
-35.55428578 26.41915557WGC cannot compute the separation angle between the Earth-Moon vectors in IAU_EARTH and ITRF93 frames. WGC cannot compute the IAU_EARTH and ITRF93 +X and +Z axis separation angles. To compute the DSS-13-Moon azimuth and elevation using a high accuracy PCK and the DSS-13_TOPO frame, specify/select the following inputs in the ``State Vector'' calculation:
Target MOON Observer DSS-13 Reference frame DSS-13_TOPO Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 State representation PlanetocentricWGC will return the following longitude and latitude, deg, that are equivalent to the azimuth (AZ=-LON) and elevation (EL=LAT):
-72.16900637 20.68948821To compute the sub-solar point on Earth using a low accuracy PCK and the IAU_EARTH frame, specify/select the following inputs in the ``Sub-Solar Point'' calculation:
Target EARTH Reference frame IAU_EARTH Observer SUN Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 Position representation PlanetocentricWGC will return the following longitude and latitude, deg:
-177.10053149 -22.91037699To compute the sub-solar point on Earth using a high accuracy PCK and the ITRF93 frame, specify/select the following inputs in the ``Sub-Solar Point'' calculation:
Target EARTH Reference frame ITRF93 Observer SUN Sub-point type Near point on ellipsoid Light propagation To observer Light-time algorithm Newtonian Stellar aberration Corrected for stellar aberration Time system UTC Time format Calendar date and time Input time 2007 JAN 1 00:00:00 Position representation PlanetocentricWGC will return the following longitude and latitude, deg:
-177.15787351 -22.91259307WGC cannot compute the distance between the sub-solar points computed in the IAU_EARTH and ITRF93 frames.
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