Upgraded UKIRT

Upgrades to the NIST/DARPA EUV reflectometry facility

Upgrading of the ESO 1.52-m telescope

Upgrading the Keck AO wavefront controllers

Upper Atmosphere Research Satellite (UARS) Solar Stellar Irradiance Comparison Experiment (SOLSTICE)

Upper limit to the thermal coefficient of the refractive index of fused silica at 184.9 nm

Uranian Equinoctial Observations

Uranus 2000 - New Images, New Spectra, and a New Look

Uranus at equinox: Cloud morphology and dynamics

Uranus's ring 1986U2R detected with Keck AO at 2.2 microns

Uranus’ cloud structure and seasonal variability from Gemini-North and UKIRT observations

Urban light pollution - The effect of atmospheric aerosols on astronomical observations at night

URSULA - A twin-beam multiband computer-controlled photometer for astronomical applications

Use of a moiré deflectometer on a telescope for atmospheric turbulence measurements

Use of a neural network to control an adaptive optics system for an astronomical telescope

Use of an ac heterodyne lateral shear interferometer with real-time wavefront correction systems

Use of aspherics and colour correcting elements in the thermal infrared.

Use of beryllium for the VLT secondary mirror

Use of ceramic materials for lightweight x-ray optics

Use of dynamic holography technique for correction of aberrations in telescopes