Progress report on sodium laser monitoring for laser guide star adaptive optics

Laser guide star adaptive optics will be implemented at all major observatories in the next decade. In this paper, we describe an experiment to monitor the short and long timescale variations of the altitude profile of mesospheric sodium. This experiment will provide information that will help in the specification and design of the laser guide star system that we hope to install at the William Herschel Telescope and commission in 2003/4.