
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:
V_{S/C}(x) = 0.866025
V_{S/C}(y) = 0.353553
V_{S/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 )
A_{1}= .288 B_{1}= .891 ω_{1}= 53.1951
A_{2}= 6.104 B_{2}= 3.159 ω_{2}= 36.6355
A_{3}= 3.104 B_{3}= 6.075 c_{1}= 2.6714
A_{4}= .027 B_{4}= .103 c_{2}= 53.1951
A_{5}= .036 B_{5}= .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 V_{GSE} = M * V_{S/C} :
Vgse(x)= 0.824126
Vgse(y)=0.470072
Vgse(z)=0.315989
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