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1 June 1994Gear error corrections on the Anglo-Australian Telescope
The Anglo-Australian Telescope's horseshoe equatorial mount is driven from its northern end by a 3.6-meter diameter straight-spur gearwheel. The telescope's tracking performance depends critically on the accuracy of this gearwheel and on the gearbox which couples it to the hour-angle encoder system. Early tests on the telescope showed that the gear systems were very accurate, though some small errors were detected. Analysis of autoguider records obtained during the period 1990-93 have recently been used to calibrate these errors, and software to apply appropriate corrections have been added to the AAT control system. In tests of the new software, a 15-minute unguided CCD exposure showed circular 0.9 arcsec FWHM star images; a similar exposure with the corrections disabled had trailed images where the east-west FWHM had worsened to 1.5 arcsec.
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Patrick T. Wallace, Steve Lee, "Gear error corrections on the Anglo-Australian Telescope," Proc. SPIE 2199, Advanced Technology Optical Telescopes V, (1 June 1994); https://doi.org/10.1117/12.176174