[Spice_discussion] spkezr vs Geocentric Solar Ecliptic (GSE) Frame
Donald F. Linton
lintond at gmail.com
Wed Jan 27 16:33:48 PST 2016
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
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