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Paper: Application of a Kalman Filter at UKIRT
Volume: 216, Astronomical Data Analysis Software and Systems IX
Page: 279
Authors: Yang, Y.; Rees, N. P.; Chuter, T.
Abstract: The tracking (i.e. unguided) performance of the United Kingdom Infra-Red Telescope (UKIRT) relies on the accuracy of its 24 bit absolute encoders. These have been long known to generate two systematic errors. The first is a periodic error resulting from the encoder deriving the last 8 resolution bits by interpolation between the 2(16) rulings on its code disk. The error has exactly 2(16) periods per revolution. The second error is quantization noise at the level of the 24(th) bit. A filter has been designed to reduce these effects and it has been inserted in the feedback loop of the telescope mount servo. Engineering tests and observers reports have noted a marked improvement in the telescope's tracking performance.
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