THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT
1997

3.3. Telescope Performance

Absolute pointing accuracy, which had improved dramatically in 1996, maintained its outstanding performance at 1.5 arcsec rms. Three significant improvements to existing Upgrades systems were made: (1) The performance of the tip/tilt and fast guide systems were enhanced; (2) auto-focus tracking (adjusting for changes in temperature of the telescope and telescope elevation) was successfully installed; and (3) primary mirror figure as a function of telescope position was adjusted using an empirically-based look-up table. The result was significant further improvement in image quality. At the start of the year sub-arcsecond images of point sources in the K band were the norm. By the second half of the year stellar images were often below 0.5 arcseconds (FWHM) and occasionally below 0.3 arcseconds. Toward the end of the year the controls for the new dome ventilation were installed and the use of the system began; the extent of its effect on the image quality was not yet determined at year's end.