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The coarse sun sensor assembly consists of two identical half sphere sensors, providing complete 4 steradian sun direction information. Each sensor provides angle information of the sun line with respect to two perpendicular axes.
The spacecraft coordinate system is right handed ( ). The axis points towards the sun within 20 .
The symmetry axis of the sensors is mounted in-line with the - axis and + axis, respectively. The sensor outputs correspond to one angle in the -plane and one angle in the -plane with nominal zero output when the sun is in the - or - direction.
The sensitivity for the inner region ( 0.1 rad) is of the order of 100 mV/rad within either of the symmetry planes ( -plane or -plane of the sensor). The output is a monotonic characteristic between -83 and +83 . Between 83 and 97 the characteristic decays linearly to zero.
|Zero bias error||0.50|
|Tolerances on 83 , 97 points||10|
|Tolerances on output voltage||5% when illuminated with 1 solar constant|
The measurement performance parameters are given in Tab. 1.2.
After the Y-gyro loss, the CSS has been used for coarse target acquisition. A software patch in the AMCE was designed and tested, and has been in operation since the start of 1991 October. After the Z-gyro loss in 1993 October, the CSS has been used together with the magnetometer, the S-gyro, and the degraded X-gyro for attitude control.