[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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