Tail Probe is a spin-stabilized spacecraft spinning around the main axis of the maximum moment of inertia. The angle between the spin axis and direction towards the Sun should not exceed a certain value.
As this angle increases with the rate of about 1o/day (because of the Earth orbital motion) the attitude control system periodically (once per ~7 days) restores the direction of the spin axis to the Sun.
To know the spacecraft attitude for a given time we use a matrix N to transform any vector V from the Geocentric Solar-Ecliptic (GSE) coordinate system to the Spacecraft Construction (S/C) coordinate system
VS/C = N * VGSE
or a matrix M for the inverse transformation
VGSE = M * VS/C
The both systems S/C and GSE are spacecraft-centered ones.
By attitude sensors data processing the attitude coefficients arrays have been obtained. It gives the possibility to calculate matrixes N,M for a given time.
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