[Spice_discussion] spkezr vs Geocentric Solar Ecliptic (GSE) Frame

William Thompson William.T.Thompson at nasa.gov
Fri Jan 29 10:58:44 PST 2016


Okay, so STEREO and Van Allen are using the exact same definition of GSE, that's 
good.

On 01/29/16 12:06, Stephens, Grant K. wrote:
> Bill,
>
> Van Allen Probes defines the MEAN_ECLIP frame as follows, which looks the
> same as the ECLIPDATE frame.
>
>
> \begindata
>
>        FRAME_MEAN_ECLIP               =  -362913
>        FRAME_-362913_NAME             =  'MEAN_ECLIP'
>        FRAME_-362913_CLASS            =  5
>        FRAME_-362913_CLASS_ID         =  -362913
>        FRAME_-362913_CENTER           =  399
>        FRAME_-362913_RELATIVE         = 'J2000'
>        FRAME_-362913_DEF_STYLE        = 'PARAMETERIZED'
>        FRAME_-362913_FAMILY           = 'MEAN_ECLIPTIC_AND_EQUINOX_OF_DATE'
>        FRAME_-362913_PREC_MODEL       = 'EARTH_IAU_1976'
>        FRAME_-362913_OBLIQ_MODEL      = 'EARTH_IAU_1980'
>        FRAME_-362913_ROTATION_STATE   = 'ROTATING'
>
>        \begintext
>
>
>
> Grant
>
> On 1/29/16 11:51 AM, "spice_discussion-bounces at naif.jpl.nasa.gov on behalf
> of William Thompson" <spice_discussion-bounces at naif.jpl.nasa.gov on behalf
> of William.T.Thompson at nasa.gov> wrote:
>
>> I tried using these three different definitions of GSE in SPKEZR.  When I
>> put
>> Earth in for both the target and the observing body, I get all zeros for
>> all
>> three definitions, as you would expect.  When I then try to put in a
>> different
>> body than Earth for the target, I get an error message for the Van Allen
>> definition:
>>
>> % CSPICE_SPKEZR: SPICE(NOTRANSLATION):
>> [spkezr_c->SPKEZR->SPKEZ->SPKGEO->FRMCHG->FRMGET->ZZDYNFRM->ZZDYNFID] The
>> kernel
>>                    variable FRAME_-362930_SEC_FRAME used to define frame
>> BRIDGMAN is assigned the character value MEAN_ECLIP.
>>                     This value was expected to be a reference frame name,
>> but
>> NAMFRM cannot translate this name to a frame ID
>>                    code.
>> % Execution halted at: $MAIN$
>>
>> (I renamed GSE to BRIDGMAN or LINTON to allow all three definitions to be
>> loaded
>> simultaneously.)  The Van Allen definition must include a definition for
>> MEAN_ECLIP frame.  However, the same is true of the STEREO definition,
>> which
>> includes a reference to the ECLIPDATE frame defined below:
>>
>> \begindata
>>
>>          FRAME_ECLIPDATE              =  1803321
>>          FRAME_1803321_NAME           = 'ECLIPDATE'
>>          FRAME_1803321_CLASS          =  5
>>          FRAME_1803321_CLASS_ID       =  1803321
>>          FRAME_1803321_CENTER         =  399
>>          FRAME_1803321_RELATIVE       = 'J2000'
>>          FRAME_1803321_DEF_STYLE      = 'PARAMETERIZED'
>>          FRAME_1803321_FAMILY         =
>> 'MEAN_ECLIPTIC_AND_EQUINOX_OF_DATE'
>>          FRAME_1803321_PREC_MODEL     = 'EARTH_IAU_1976'
>>          FRAME_1803321_OBLIQ_MODEL    = 'EARTH_IAU_1980'
>>          FRAME_1803321_ROTATION_STATE = 'ROTATING'
>>
>> \begintext
>>
>> It's possible this is the same as MEAN_ECLIP in the Van Allen definition.
>> I
>> realize now that everything else in the STEREO and Van Allen definitions
>> of GSE
>> is the same.
>>
>> When I apply the Linton and STEREO definitions of GSE to Mars for the ET
>> value
>> in the original mail message, I get the following values:
>>
>> STEREO definition:
>>     3.8803534e+08       54357681.       6945416.9       6.9416565
>> -23.066438      0.37886396
>>
>> Linton definition:
>>     3.8803534e+08       54357885.       6943816.8       6.9416565
>> -23.066896      0.38321554
>>
>> Difference:
>>         0.0000000      -204.42863       1600.1297       0.0000000
>> 0.00045798140   -0.0043515797
>>
>> The light travel times are the same for both definitions.
>>
>> Bill Thompson
>>
>>
>> On 01/29/16 11:17, William Thompson wrote:
>>> The STEREO project has been using a different definition for GSE.  I'll
>>> have to
>>> take a look at how all these frames differ.  The definition below is in
>>> the file
>>>
>>>
>>> http://sohowww.nascom.nasa.gov/solarsoft/stereo/gen/data/spice/gen/helios
>>> pheric.tf
>>>
>>> Bill Thompson
>>>
>>>
>>> \begindata
>>>
>>>           FRAME_GSE                    =  1803311
>>>           FRAME_1803311_NAME           = 'GSE'
>>>           FRAME_1803311_CLASS          =  5
>>>           FRAME_1803311_CLASS_ID       =  1803311
>>>           FRAME_1803311_CENTER         =  399
>>>           FRAME_1803311_RELATIVE       = 'J2000'
>>>           FRAME_1803311_DEF_STYLE      = 'PARAMETERIZED'
>>>           FRAME_1803311_FAMILY         = 'TWO-VECTOR'
>>>           FRAME_1803311_PRI_AXIS       = 'X'
>>>           FRAME_1803311_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION'
>>>           FRAME_1803311_PRI_OBSERVER   = 'EARTH'
>>>           FRAME_1803311_PRI_TARGET     = 'SUN'
>>>           FRAME_1803311_PRI_ABCORR     = 'NONE'
>>>           FRAME_1803311_SEC_AXIS       = 'Z'
>>>           FRAME_1803311_SEC_VECTOR_DEF = 'CONSTANT'
>>>           FRAME_1803311_SEC_FRAME      = 'ECLIPDATE'
>>>           FRAME_1803311_SEC_SPEC       = 'RECTANGULAR'
>>>           FRAME_1803311_SEC_VECTOR     = ( 0, 0, 1 )
>>>
>>> \begintext
>>>
>>>
>>> On 01/29/16 10:24, William T Bridgman wrote:
>>>> A tf file for the Van Allen probes has a different definition to build
>>>> GSE:
>>>>
>>>>         \begindata
>>>>
>>>>         FRAME_GSE                    = -362930
>>>>         FRAME_-362930_NAME           = 'GSE'
>>>>         FRAME_-362930_CLASS          = 5
>>>>         FRAME_-362930_CLASS_ID       = -362930
>>>>         FRAME_-362930_CENTER         = 399
>>>>         FRAME_-362930_RELATIVE       = 'J2000'
>>>>         FRAME_-362930_DEF_STYLE      = 'PARAMETERIZED'
>>>>         FRAME_-362930_FAMILY         = 'TWO-VECTOR'
>>>>         FRAME_-362930_PRI_AXIS       = 'X'
>>>>         FRAME_-362930_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION'
>>>>         FRAME_-362930_PRI_OBSERVER   = 'EARTH'
>>>>         FRAME_-362930_PRI_TARGET     = 'SUN'
>>>>         FRAME_-362930_PRI_ABCORR     = 'NONE'
>>>>         FRAME_-362930_SEC_AXIS       = 'Z'
>>>>         FRAME_-362930_SEC_VECTOR_DEF = 'CONSTANT'
>>>>         FRAME_-362930_SEC_SPEC       = 'RECTANGULAR'
>>>>         FRAME_-362930_SEC_FRAME      = 'MEAN_ECLIP'
>>>>         FRAME_-362930_SEC_VECTOR     = (0, 0, 1)
>>>>
>>>>         \begintext
>>>>
>>>> It defines the secondary as z-axis rather than y-axis.  I suspect your
>>>> y-axis is
>>>> not quite perpendicular to your x-axis which might be projecting some
>>>> velocity
>>>> in the x-direction.
>>>>
>>>> Tom
>>>>
>>>> On 1/27/16 7:33 PM, Donald F. Linton wrote:
>>>>> I implemented the Geocentric Solar Ecliptic (GSE) Frame in the Frames
>>>>>
>>>>> <http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/req/frames.html
>>>>> #Specifying
>>>>>
>>>>>
>>>>> a New Frame> reference:
>>>>>
>>>>> \begindata
>>>>>      FRAME_GSE                       =  314101
>>>>>      FRAME_314101_NAME           = 'GSE'
>>>>>      FRAME_314101_CLASS          =  5
>>>>>      FRAME_314101_CLASS_ID       =  314101
>>>>>      FRAME_314101_CENTER         =  399
>>>>>      FRAME_314101_RELATIVE       = 'J2000'
>>>>>      FRAME_314101_DEF_STYLE      = 'PARAMETERIZED'
>>>>>      FRAME_314101_FAMILY         = 'TWO-VECTOR'
>>>>>      FRAME_314101_PRI_AXIS       = 'X'
>>>>>      FRAME_314101_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION'
>>>>>      FRAME_314101_PRI_OBSERVER   = 'EARTH'
>>>>>      FRAME_314101_PRI_TARGET     = 'SUN'
>>>>>      FRAME_314101_PRI_ABCORR     = 'NONE'
>>>>>      FRAME_314101_SEC_AXIS       = 'Y'
>>>>>      FRAME_314101_SEC_VECTOR_DEF = 'OBSERVER_TARGET_VELOCITY'
>>>>>      FRAME_314101_SEC_OBSERVER   = 'EARTH'
>>>>>      FRAME_314101_SEC_TARGET     = 'SUN'
>>>>>      FRAME_314101_SEC_ABCORR     = 'NONE'
>>>>>      FRAME_314101_SEC_FRAME      = 'J2000'
>>>>> \begintext
>>>>>
>>>>> Using the epoch: 2017-07-01T00:00:00
>>>>> et = 5.521392681841135e8
>>>>>
>>>>> sv = spkezr( "SUN", et, "J2000", "NONE", "EARTH" )
>>>>>
>>>>>    -2.41323e7  1.37774e8  5.97261e7  -28.9257  -4.24521  -1.83927
>>>>>
>>>>> then
>>>>>
>>>>> M = sxform("J2000", "GSE", et )
>>>>>
>>>>>    -0.158671     0.905874      0.392703     0.0          0.0        0.0
>>>>>    -0.987331    -0.145594     -0.0630798    0.0          0.0        0.0
>>>>>     3.26993e-5  -0.397737      0.9175       0.0          0.0        0.0
>>>>>    -1.90166e-7  -2.80422e-8   -1.21495e-8  -0.158671     0.905874
>>>>> 0.392703
>>>>>     3.0561e-8   -1.7445e-7    -7.56986e-8  -0.987331    -0.145594
>>>>> -0.0630798
>>>>>    -6.6631e-11  -9.82553e-12  -4.257e-12    3.26993e-5  -0.397737
>>>>> 0.9175
>>>>>
>>>>> M*SV yields
>>>>>
>>>>>    1.5209e8
>>>>>    2.79397e-9
>>>>>    7.45058e-9
>>>>>    0.0217735
>>>>>    6.64746e-15
>>>>>    2.22045e-16
>>>>>
>>>>> I don't understand why I see 21.77 m/s of sunward velocity
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Spice_discussion mailing list
>>>>> Spice_discussion at naif.jpl.nasa.gov
>>>>> https://naif.jpl.nasa.gov/mailman/listinfo/spice_discussion
>>>>>
>>>>
>>>
>>
>> --
>> William Thompson
>> NASA Goddard Space Flight Center
>> Code 671
>> Greenbelt, MD  20771
>> USA
>>
>> 301-286-2040
>> William.T.Thompson at nasa.gov
>> _______________________________________________
>> Spice_discussion mailing list
>> Spice_discussion at naif.jpl.nasa.gov
>> https://naif.jpl.nasa.gov/mailman/listinfo/spice_discussion
>
>

-- 
William Thompson
NASA Goddard Space Flight Center
Code 671
Greenbelt, MD  20771
USA

301-286-2040
William.T.Thompson at nasa.gov


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