 
Brief Guide to Doing SPICE Hands-On Lessons Using WGC
===========================================================================
 
   May 21, 2018
 
 
Overview
--------------------------------------------------------
 
   This guide provides brief instructions on how to do SPICE ``Remote
   Sensing'' (CASSINI and ExoMars 2016), ``In-situ Sensing'', ``Geometric
   Event Finding'' (Mars Express and ExoMars 2016), and ``Binary PCK''
   hands-on lessons using the SPICE WebGeocalc (WGC) tool.
 
   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
 
   WGC at NAIF can be accessed at:
 
      http://wgc.jpl.nasa.gov:8080/webgeocalc/#NewCalculation
 
   WGC at ESAC can be accessed at:
 
      http://spice.esac.esa.int/webgeocalc/#NewCalculation
 
   The WGC tutorial and examples are linked from the WGC introduction page
   on the NAIF server:
 
      http://naif.jpl.nasa.gov/naif/webgeocalc.html
 
 
``CASSINI Remote Sensing'' Hands-On Lesson Using WGC
--------------------------------------------------------
 
 
Kernels Used
 
   Use the ``SPICE Class - CASSINI Remote Sensing Lesson Kernels'' kernel
   set appearing near the bottom of the ``Kernel selection:'' menu to do
   all steps in this lesson.
 
 
Time Conversion (convtm)
 
   To compute ET seconds past J2000, 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
      Output time format        Seconds past J2000
 
   WGC will return the following ET seconds past J2000:
 
      140254384.184620
 
   To 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        TDB
 
   WGC will return the following calendar ET time string:
 
      2004-06-11 19:33:04.184625 TDB
 
   To 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 ::TDB
 
   WGC will return the following calendar ET time string:
 
      2004-JUN-11T19:33:04
 
   To 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
 
 
Time Conversion -- Selected Extra Credit
 
   1. To compute TDB Julian Date, 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
      Output time format        Julian Date
 
   WGC will return the following SCLK time string:
 
      2453168.314631800 JD TDB
 
   5. To compute the earliest UTC time that can be converted to CASSINI
   spacecraft clock, specify/select the following inputs in the ``Time
   Conversion'' calculation:
 
      Time system               Spacecraft clock (SCLK=-82)
      Time format               Spacecraft clock ticks
      Input time                0.0
      Output time system        UTC
      Output time format        Calendar (year-month-day)
 
   WGC will return the following UTC time string:
 
      1980-01-01 00:00:00.000000 UTC
 
   6. To convert 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=-82)
      Time format               Spacecraft clock string
      Input time                1/1465674964.105
      Output time system        UTC
      Custom format             YYYY-MM-DDTHR:MN:SC.### ::RND
 
   WGC will return the following UTC time string:
 
      2004-06-11T19:31:59.999
 
 
Obtaining Target States and Positions (getsta)
 
   To compute the apparent state of Phoebe as seen from CASSINI in the
   J2000 frame, specify/select the following inputs in the ``State Vector''
   calculation:
 
      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      Rectangular
 
   WGC will return the following state vector, km and km/s:
 
      -119.92092897
      2194.13933986
      -57.63897986
      -5.98023114
      -2.11880531
      -0.29482213
 
   To 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      Rectangular
 
   WGC will return the following position vector, km, and one way light
   time, s:
 
      353019393.12261910
      -1328180352.14030500
      -568134171.69730540
      4960.42691203
 
   To 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      Rectangular
 
   WGC will return the following position vector, km:
 
      376551465.27159620
      -1190495630.30282120
      -508438699.11000470
 
   Note that WGC will also compute the distance between Sun and Phoebe body
   centers, km:
 
      1348176829.09957000
 
   but it cannot convert this distance to AUs.
 
 
Obtaining Target States and Positions -- Selected Extra Credit
 
   5. To compute the position of the Sun as seen from Saturn in the J2000
   using the following light time and aberration corrections: NONE, LT and
   LT+S, manually load the additional SPK used in the hands-on lesson
   (generic_kernels/spk/satellites/a_old_versions/jup310_2004.bsp) and
   specify/select the following inputs in the ``State Vector'' calculation
   (except for corrections):
 
      Target                    SUN
      Observer                  SATURN
      Reference frame           J2000
      Time system               UTC
      Time format               Calendar date and time
      Input time                2004 JUN 11 19:32:00
      State representation      Rectangular
 
   and 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 aberration
 
   WGC will return the following position vectors, km, correspondingly:
 
      367770592.36738380
      -1197330367.35880470
      -510369088.67673343
 
      367770572.92069393
      -1197330417.73307600
      -510369109.50883270
 
      367726456.16774523
      -1197342627.87914750
      -510372252.74684080
 
 
Spacecraft Orientation and Reference Frames (xform)
 
   To compute the apparent state of Phoebe as seen from CASSINI in the
   IAU_PHOEBE body-fixed frame, specify/select the following inputs in the
   ``State Vector'' calculation:
 
      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      Rectangular
 
   WGC will return the following state vector, km and km/s:
 
      -1982.63976162
      -934.53047112
      -166.56259513
      3.97083213
      -3.81249566
      -2.37166299
 
   WGC 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 (HGA) 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      Spherical
 
   WGC will return the following output colatitude, deg:
 
      71.92414848
 
 
Spacecraft Orientation and Reference Frames -- Selected Extra Credit
 
   2. To compute the angular separation between the apparent position of
   Sun and the CASSINI HGA nominal boresight to find out if HGA is
   illuminated, specify/select the following inputs in the ``State Vector''
   calculation:
 
      Target                    SUN
      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                2018 JUN 11 19:32:00
      State representation      Spherical
 
   WGC will return the following output colatitude, deg:
 
      73.12975130
 
   This angle is less than 90 degrees so the HGA is illuminated.
 
 
Computing Sub-s/c and Sub-solar Points on an Ellipsoid and a DSK (subpts)
 
   To compute the apparent sub-observer point of CASSINI on Phoebe modeled
   as an ellipsoid in the IAU_PHOEBE frame, specify/select the following
   inputs in the ``Sub-Observer Point'' calculation:
 
      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   Rectangular
 
   WGC will return the following position vector, km:
 
      104.49789074
      45.26884577
      7.38331473
 
   Note 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:
 
      2084.11604205
 
   To compute the apparent sub-solar point on Phoebe modeled as an
   ellipsoid 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   Rectangular
 
   WGC will return the following position vector, km:
 
      78.68071625
      76.87865160
      -21.88456729
 
   WGC cannot compute the sub-spacecraft and sub-solar points on a DSK.
 
 
Computing Sub-spacecraft and Sub-solar Points -- Selected Extra Credit
 
   1. To compute the apparent sub-solar point on Phoebe as seen from
   CASSINI in the IAU_PHOEBE frame using the ``Intercept: ellipsoid''
   method, 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            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   Rectangular
 
   WGC will return the following position vector, km:
 
      74.54229300
      79.60686277
      -24.87078454
 
   2. To compute the geometric sub-observer point of CASSINI on Phoebe in
   the IAU_PHOEBE frame using the 'Near point: ellipsoid' method,
   specify/select the following inputs in the ``Sub-Observer Point''
   calculation:
 
      Calculation type          Sub-Observer Point
      Target                    PHOEBE
      Reference frame           IAU_PHOEBE
      Observer                  CASSINI
      Sub-point type            Near point on ellipsoid
      Light propagation         No correction
      Time system               UTC
      Time format               Calendar date and time
      Input time                2004 JUN 11 19:32:00
      Position representation   Rectangular
 
   WGC will return the following position vector, km:
 
      104.49708353
      45.27041148
      7.38409174
 
   3. To compute the planetocentric coordinates of the geometric
   sub-observer point of CASSINI on Phoebe in the IAU_PHOEBE frame,
   specify/select the following inputs in the ``Sub-Observer Point''
   calculation:
 
      Calculation type          Sub-Observer Point
      Target                    PHOEBE
      Reference frame           IAU_PHOEBE
      Observer                  CASSINI
      Sub-point type            Near point on ellipsoid
      Light propagation         No correction
      Time system               UTC
      Time format               Calendar date and time
      Input time                2004 JUN 11 19:32:00
      Position representation   Planetocentric
 
   WGC will return the following latitude and longitude, deg, and radius,
   km:
 
      3.70986500
      23.42331102
      114.12088079
 
   WGC 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, PHOEBE, has equatorial axes
      that differ, 115.0 and 110.0. Use planetocentric coordinates
      instead.
 
 
Intersecting Vectors with an Ellipsoid and a DSK (fovint)
 
   To compute the Cartesian position vectors of the FOV boundary vector
   surface intercept points on the surface of Phoebe modeled as an
   ellipsoid 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   Rectangular
 
   WGC will return the following position vectors, km:
 
      91.02635667
      67.19017758
      2.03016242
 
      89.99095003
      66.72560204
      14.73282379
 
      80.96314734
      76.64306316
      14.42662102
 
      81.99683969
      77.10572511
      1.69850758
 
   To compute the planetocentric longitudes and latitudes of the FOV
   boundary vector surface intercept points on the surface of Phoebe
   modeled as an ellipsoid 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   Planetocentric
 
   WGC will return the following longitudes and latitudes, deg:
 
      36.43251123
      1.02800787
 
      36.55583078
      7.49186596
 
      43.42988023
      7.37325329
 
      43.23917363
      0.86454948
 
   Both 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 on the surface of Phoebe modeled as an ellipsoid 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   Rectangular
 
   WGC will return the following position vector, km:
 
      86.39001297
      72.08919557
      8.25459687
 
   To compute the planetocentric longitude and latitude of the FOV
   boresight surface intercept point on the surface of Phoebe modeled as an
   ellipsoid 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   Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      39.84371945
      4.19587780
 
   and the following incidence, emission, and phase angles, deg:
 
      18.24722120
      17.85830930
      28.13948173
 
   WGC cannot compute the surface intercept points on a DSK and the local
   solar time at the boresight intercept point.
 
 
``ExoMars 2016 Remote Sensing'' Hands-On Lesson Using WGC
--------------------------------------------------------
 
 
Kernels Used
 
   Use the ``SPICE Class - ExoMars 2016 Remote Sensing Lesson Kernels''
   kernel set appearing near the bottom of the ``Kernel selection:'' menu
   to do all steps in this lesson.
 
 
Time Conversion (convtm)
 
   To compute ET seconds past J2000, 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        Seconds past J2000
 
   WGC will return the following ET seconds past J2000:
 
      582017589.184640
 
   To 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 19:33:09.184642
 
   To 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 ::TDB
 
   WGC will return the following calendar ET time string:
 
      2018-JUN-11T19:33:09
 
   To 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 string
 
   WGC will return the following SCLK time string:
 
      1/0070841719.26698
 
 
Time Conversion -- Selected Extra Credit
 
   1. To compute TDB Julian Date, 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        Julian Date
 
   WGC will return the following SCLK time string:
 
      2458281.314689600 JD TDB
 
   5. 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 ticks
      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 UTC
 
   6. To convert 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.### ::RND
 
   WGC will return the following UTC time string:
 
      2018-06-11T19:32:00.000
 
 
Obtaining Target States and Positions (getsta)
 
   To compute the apparent state of Mars as seen from TGO in the J2000
   frame, specify/select the following inputs in the ``State Vector''
   calculation:
 
      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      Rectangular
 
   WGC will return the following state vector, km and km/s:
 
      2911.82242547
      -2033.80245966
      -1291.70085522
      1.30950490
      -0.05597018
      3.10432898
 
   To 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      Rectangular
 
   WGC will return the following position vector, km, and one way light
   time, s:
 
      -49609884.08045448
      57070665.86178913
      30304236.92973865
      271.73803215
 
   To 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      Rectangular
 
   WGC will return the following position vector, km:
 
      -24712734.28893231
      194560532.94319060
      89906636.78934350
 
   Note that WGC will also compute the distance between Sun and Mars body
   centers, km:
 
      215749214.49206870
 
   but it cannot convert this distance to AUs.
 
 
Obtaining Target States and Positions -- Selected Extra Credit
 
   4. To compute the position of the Sun as seen from Mars in the J2000
   using the following light time and aberration corrections: NONE, LT and
   LT+S, specify/select the following inputs in the ``State Vector''
   calculation (except for corrections):
 
      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      Rectangular
 
   and 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 aberration
 
   WGC 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)
 
   To compute the apparent state of Mars as seen from TGO in the IAU_MARS
   body-fixed frame, specify/select the following inputs in the ``State
   Vector'' calculation:
 
      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      Rectangular
 
   WGC will return the following state vector, km and km/s:
 
      -2843.46412456
      2235.45954373
      1095.89496870
      0.31144328
      -1.15192925
      3.08212262
 
   WGC 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      Spherical
 
   WGC will return the following output colatitude, deg:
 
      5.43847143
 
 
Spacecraft Orientation and Reference Frames -- Selected Extra Credit
 
   2. To compute the angular separation between the apparent position of
   Sun and the TGO nominal instrument view direction to find out if the
   science deck illuminated, specify/select the following inputs in the
   ``State Vector'' calculation:
 
      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      Spherical
 
   WGC will return the following output colatitude, deg:
 
      130.54279733
 
   This angle is greater than 90 degrees so the science deck is not
   illuminated.
 
 
Computing Sub-s/c and Sub-solar Points on an Ellipsoid and a DSK (subpts)
 
   To compute the apparent sub-observer point of TGO on Mars in the
   IAU_MARS frame using the ``Near point: ellipsoid'' method,
   specify/select the following inputs in the ``Sub-Observer Point''
   calculation:
 
      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   Rectangular
 
   WGC will return the following position vector, km:
 
      2554.16465516
      -2008.01038262
      -983.24042077
 
   Note 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:
 
      385.04529279
 
   To 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   Rectangular
 
   WGC will return the following position vector, km:
 
      487.58869797
      -3348.61049793
      -286.69722014
 
   WGC cannot compute the sub-spacecraft and sub-solar points on a DSK.
 
 
Computing Sub-spacecraft and Sub-solar Points -- Selected Extra Credit
 
   1. To compute the apparent sub-solar point on Mars as seen from TGO in
   the IAU_MARS frame using the ``Intercept: 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            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   Rectangular
 
   WGC will return the following position vector, km:
 
      487.54669671
      -3348.32205372
      -290.07721511
 
   2. To compute the apparent sub-observer point of TGO on Phobos in the
   IAU_PHOBOS frame using the 'Near point: ellipsoid' method,
   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   Rectangular
 
   WGC will return the following position vector, km:
 
      12.05913904
      4.17308831
      -0.67546616
 
   3. To compute the planetocentric coordinates of the apparent
   sub-observer point of TGO on Phobos in the IAU_PHOBOS frame using the
   'Near point: ellipsoid' method, 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   Planetocentric
 
   WGC will return the following latitude and longitude, deg, and radius,
   km:
 
      -3.03000878
      19.08827715
      12.77864449
 
   WGC 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 an Ellipsoid and a DSK (fovint)
 
   To compute the Cartesian position vectors of the FOV boundary vector
   surface intercept points on the surface of Mars modeled as an ellipsoid
   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   Rectangular
 
   WGC will return the following position vectors, km:
 
      2535.00445179
      -2028.52838809
      -990.59432639
 
      2525.05593461
      -2042.07461651
      -988.19646467
 
      2525.20138167
      -2042.10358036
      -987.76992477
 
      2535.14886773
      -2028.55774855
      -990.16957287
 
   To compute the planetocentric longitudes and latitudes of the FOV
   boundary vector surface intercept points on the surface of Mars modeled
   as an ellipsoid 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   Planetocentric
 
   WGC will return the following longitudes and latitudes, deg:
 
      -38.66704048
      -16.96728341
 
      -38.96331703
      -16.92492977
 
      -38.96210076
      -16.91739679
 
      -38.66585276
      -16.95978024
 
   Both 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 on the surface of Mars modeled as an ellipsoid 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   Rectangular
 
   WGC will return the following position vector, km:
 
      2530.12229730
      -2035.30663798
      -989.18816471
 
   To compute the planetocentric longitude and latitude of the FOV
   boresight surface intercept point on the surface of Mars modeled as an
   ellipsoid 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   Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      -38.81424755
      -16.94244506
 
   and the following incidence, emission, and phase angles, deg:
 
      43.72871855
      6.08637448
      49.45727680
 
   WGC cannot compute the surface intercept points on a DSK and the local
   solar time at the boresight intercept point.
 
 
``In-situ Sensing'' Hands-On Lesson Using WGC
--------------------------------------------------------
 
 
Kernels Used
 
   Use the ``SPICE Class - In-situ Sensing Lesson Kernels'' kernel set
   appearing near the bottom of the ``Kernel selection:'' menu to do all
   steps in this lesson.
 
 
Step-1: ``UTC to ET''
 
   To compute ET seconds past J2000 for a given UTC string, specify/select
   the following inputs in the ``Time Conversion'' calculation:
 
      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 J2000
 
   WGC will return the following ET seconds past J2000:
 
      140254384.184620
 
 
Step-2: ``SCLK to ET''
 
   To compute ET seconds past J2000 for a given SCLK string, specify/select
   the following inputs in the ``Time Conversion'' calculation:
 
      Time system               Spacecraft clock (SCLK=-82)
      Time format               Spacecraft clock string
      Input time                1465674964.105
      Output time system        TDB
      Output time format        Seconds past J2000
 
   WGC will return the following ET seconds past J2000:
 
      140254384.183430
 
   Either 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''
 
   To compute the geometric state of the CASSINI spacecraft with respect to
   the Sun in the Ecliptic frame, specify/select the following inputs in
   the ``State Vector'' calculation:
 
      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      Rectangular
 
   WGC 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''
 
   To compute the apparent direction of the Sun in the INMS frame,
   specify/select the following inputs in the ``State Vector'' calculation:
 
      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      Rectangular
 
   WGC will return the following position vector, km:
 
      -391245772.45811266
      1188593024.20844320
      501745827.05297270
 
 
Step-5: ``Sub-Spacecraft Point''
 
   To compute the planetocentric longitude and latitude of the CASSINI
   sub-spacecraft point on Phoebe, specify/select the following inputs in
   the ``Sub-Observer Point'' calculation:
 
      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   Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      23.42315899
      3.70979740
 
   WGC cannot compute the direction from the CASSINI spacecraft to the
   sub-spacecraft point in the INMS frame.
 
 
Step-6: ``Spacecraft Velocity''
 
   WGC cannot calculate the CASSINI spacecraft velocity with respect to
   Phoebe in the INMS frame as described in this step of the programming
   lesson.
 
 
``Mars Express Geometric Event Finding'' Hands-On Lesson Using WGC
--------------------------------------------------------
 
 
Kernels Used
 
   Use the ``SPICE Class - Mars Express Geometric Event Finding Lesson
   Kernels'' kernel set appearing near the bottom of the ``Kernel
   selection:'' menu to do all steps in this lesson.
 
 
Find View Periods
 
   To find the set of time intervals when the Mars Express (MEX) is visible
   from the DSN station DSS-14, specify/select the following inputs in the
   ``Position Event Finder'' calculation:
 
      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 filtering
 
   WGC 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 TDB
 
   Make 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
 
   To find the set of time intervals when the Mars Express Orbiter (MEX)
   spacecraft is visible from the DSN station DSS-14 and is not occulted by
   Mars modeled as an ellipsoid, specify/select the following inputs in the
   ``Occultation Event Finder'' calculation:
 
      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 filtering
 
   To 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
 
   WGC cannot compute occultations by a body with the surface modeled by a
   DSK.
 
 
Extra Credit
 
   1. To find times when Mars Express orbiter (MEX) crosses Mars' equator,
   specify/select the following inputs in the ``Position Event Finder''
   calculation:
 
      Target                      MARS EXPRESS
      Observer                    MARS
      Reference frame             IAU_MARS
      Light propagation           No correction
      Time system                 TDB
      Time format                 Calendar date and time
      Time range                  2004 MAY 02 to 2004 MAY 06,
                                  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 filtering
 
   WGC will return the following times:
 
      2004-05-02 05:00:08.334792 TDB
      2004-05-02 06:15:13.074957 TDB
      2004-05-02 12:35:14.856242 TDB
      2004-05-02 13:50:09.161841 TDB
      2004-05-02 20:10:24.439170 TDB
      2004-05-02 21:25:10.344246 TDB
      2004-05-03 03:45:26.758446 TDB
      2004-05-03 05:00:04.086901 TDB
      2004-05-03 11:20:32.419618 TDB
      2004-05-03 12:34:57.968562 TDB
      2004-05-03 18:55:34.883629 TDB
      2004-05-03 20:09:53.063063 TDB
      2004-05-04 02:30:35.509603 TDB
      2004-05-04 03:44:42.753445 TDB
      2004-05-04 10:05:41.638033 TDB
      2004-05-04 11:19:38.397433 TDB
      2004-05-04 17:40:41.405725 TDB
      2004-05-04 18:54:31.413477 TDB
      2004-05-05 01:15:45.967991 TDB
      2004-05-05 02:29:25.294886 TDB
      2004-05-05 08:50:53.931352 TDB
      2004-05-05 10:04:26.915886 TDB
      2004-05-05 16:25:58.350272 TDB
      2004-05-05 17:39:23.889937 TDB
 
   2. To find times when Mars Express orbiter (MEX) is at periapsis,
   specify/select the following inputs in the ``Distance Event Finder''
   calculation:
 
      Target                      MARS EXPRESS
      Observer                    MARS
      Light propagation           No correction
      Time system                 TDB
      Time format                 Calendar date and time
      Time range                  2004 MAY 02 to 2004 MAY 06,
                                  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 filtering
 
   WGC will return the following times:
 
      2004-05-02 05:57:51.000411 TDB
      2004-05-02 13:32:43.325958 TDB
      2004-05-02 21:07:41.124293 TDB
      2004-05-03 04:42:30.648154 TDB
      2004-05-03 12:17:21.143198 TDB
      2004-05-03 19:52:12.267643 TDB
      2004-05-04 03:26:57.755816 TDB
      2004-05-04 11:01:49.826895 TDB
      2004-05-04 18:36:38.448012 TDB
      2004-05-05 02:11:28.558226 TDB
      2004-05-05 09:46:26.309109 TDB
      2004-05-05 17:21:18.875493 TDB
 
   3. To find times when Mars Express orbiter (MEX) is at apoapsis,
   specify/select the following inputs in the ``Distance Event Finder''
   calculation:
 
      Target                      MARS EXPRESS
      Observer                    MARS
      Light propagation           No correction
      Time system                 TDB
      Time format                 Calendar date and time
      Time range                  2004 MAY 02 to 2004 MAY 06,
                                  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 filtering
 
   WGC will return the following times:
 
      2004-05-02 02:10:24.948283 TDB
      2004-05-02 09:45:19.189323 TDB
      2004-05-02 17:20:14.194854 TDB
      2004-05-03 00:55:07.633360 TDB
      2004-05-03 08:29:57.890652 TDB
      2004-05-03 16:04:48.524492 TDB
      2004-05-03 23:39:36.745574 TDB
      2004-05-04 07:14:25.662870 TDB
      2004-05-04 14:49:15.904704 TDB
      2004-05-04 22:24:05.351784 TDB
      2004-05-05 05:58:59.270665 TDB
      2004-05-05 13:33:54.433201 TDB
      2004-05-05 21:08:50.211003 TDB
 
 
``ExoMars-16 TGO Geometric Event Finding'' Hands-On Lesson Using WGC
--------------------------------------------------------
 
 
Kernels Used
 
   Use the ``SPICE Class - ExoMars 2016 Geometric Event Finding Lesson
   Kernels'' kernel set appearing near the bottom of the ``Kernel
   selection:'' menu to do all steps in this lesson.
 
 
Find View Periods
 
   To find the set of time intervals when the ExoMars-16 TGO (TGO) is
   visible from the ESA station NEW_NORCIA, specify/select the following
   inputs in the ``Position Event Finder'' calculation:
 
      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 filtering
 
   WGC 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 TDB
 
   Make 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
 
   To find the set of time intervals when the ExoMars-16 TGO Orbiter (TGO)
   spacecraft is visible from the ESA station NEW_NORCIA and and is not
   occulted by Mars modeled as an ellipsoid, specify/select the following
   inputs in the ``Occultation Event Finder'' calculation:
 
      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 filtering
 
   To 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
 
   WGC cannot compute occultations by a body with the surface modeled by a
   DSK.
 
 
Extra Credit
 
   1. To find times when ExoMars-16 TGO (TGO) crosses Mars' equator,
   specify/select the following inputs in the ``Position Event Finder''
   calculation:
 
      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 filtering
 
   WGC 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 TDB
 
   2. 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 filtering
 
   WGC 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 TDB
 
   3. 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 filtering
 
   WGC 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 WGC
--------------------------------------------------------
 
 
Moon rotation (mrotat)
 
   Use the ``SPICE Class - Binary PCK Lesson Kernels (Moon)'' kernel set
   appearing near the bottom of the ``Kernel selection:'' menu to do this
   step in this lesson.
 
   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      Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      3.61310222
      -6.43834182
 
   To 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      Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      3.61122841
      -6.43950148
 
   WGC 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      Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      3.59331861
      -6.41758189
 
   WGC 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   Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      3.61141894
      -6.43950142
 
   To 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   Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      3.59350886
      -6.41758182
 
   WGC cannot compute the distance between the sub-Earth points computed in
   the MOON_ME and MOON_PA frames.
 
 
Earth rotation (erotat)
 
   Use the ``SPICE Class - Binary PCK Lesson Kernels (Earth)'' kernel set
   appearing near the bottom of the ``Kernel selection:'' menu to do this
   step in this lesson.
 
   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      Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      -35.49627162
      26.41695855
 
   To 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      Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      -35.55428578
      26.41915557
 
   WGC 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      Planetocentric
 
   WGC will return the following longitude and latitude, deg, that are
   equivalent to the azimuth (AZ=-LON) and elevation (EL=LAT):
 
      -72.16900637
      20.68948821
 
   To 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   Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      -177.10053149
      -22.91037699
 
   To 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   Planetocentric
 
   WGC will return the following longitude and latitude, deg:
 
      -177.15787351
      -22.91259307
 
   WGC cannot compute the distance between the sub-solar points computed in
   the IAU_EARTH and ITRF93 frames.
 
