1 Introduction

 

Adaptive optics for 8-m class telescopes is essential if their full potential is to be realised, and in order to achieve maximal sky coverage the use of laser guide stars is mandatory. Considerable effort has been put into developing high-order AO instrumentation and observational programmes: the number of refereed papers based on AO has been increasing dramatically (27 in 1997 compared to only 18 in the entire 4 years prior to that, Ridgway 1998), and recently an entire meeting was devoted to scientific results using adaptive optics systems (Astronomy with Adaptive Optics, ESO 1998). However, this also highlighted the fact that nearly all observations to date have been restricted to imaging studies, almost exclusively using natural guide stars as the wavefront reference. Further, the majority of results have been concerned with stellar systems and relatively few have been on extragalactic sources. This bias is simply a result of the lack of suitable reference stars since the most commonly observed extragalactic objects lie out of the galactic plane, while most bright stars lie in the galactic plane; and with the exception of a few of the brightest AGN, the nuclei of other galaxies are too faint for wavefront sensing with current technology.

Clearly, there is a need for development in the areas of artifical guide stars and diffraction-limited spectroscopy. But technical difficulties have slowed progress in producing high quality LGS, and practical difficulties have hindered advances in high spatial resolution spectroscopy. ALFA (Adaptive optics with a Laser For Astronomy, see Sect. 2) is addressing these issues and has made significant progress in both areas. In this paper we present some of our first observational results, which include these two areas. We begin by noting in Sect. 3 the best performance that ALFA has achieved, in context with other systems. In Sect. 4 the first spectroscopy at diffraction limited scales is presented. Section 5 continues with observations of an $80''\times80''$ field around a Herbig Ae/Be star, looking at a binary, circumstellar envelopes, and the AO performance off-axis. The results from imaging a galaxy using the laser guide star as a wavefront reference are given in Sect. 6.