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The software includes:
attidf.for - a FORTRAN subroutine to get a matrix M (named PA in the subroutine text) to transform any vector from the S/C coordinate system to the GSE coordinate system:
To transform a vector from the GSE coordinate system to the S/C coordinate system transpose the matrix M:
You can download subroutine.
Here is an example of using the subroutine attidf.for
Let us suppose that we have a direction in the S/C frame:
VS/C(x) = 0.866025
VS/C(y) = 0.353553
VS/C(z) = 0.353553
We want to know the direction of this vector in the GSE frame for date: 30.05.1997, time 1h.0min.0sec. ut.
We use the line in attitude coefficients arrays corresponding to an attitude coefficients data set for the given interval.
interval beginning: date 97.05.30, time 2.104 thousands of sec
interval duration: 4.594 thousands of sec.
Our time of interest (3.6 thousands of sec) is within the interval.
We use the subroutine {attidf}.
Our input parameters :
ts=1.496 (which is 3.6 (the time of interest) minus 2.104 )
A1= -.288 B1= .891 ω1= 53.1951
A2= 6.104 B2= -3.159 ω2= 36.6355
A3= 3.104 B3= 6.075 c1= 2.6714
A4= -.027 B4= -.103 c2= -53.1951
A5= -.036 B5= -.077
The result is the matrix of transformation M:
0.993484 -0.113452 0.010904
M= -0.112566 -0.991700 -0.062135
0.017862 0.060503 -0.998008
So the vector in the GSE system equals to VGSE = M * VS/C :
Vgse(x)= 0.824126
Vgse(y)=-0.470072
Vgse(z)=-0.315989
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