NAOMI/OASIS on-sky performance

NAOMI is the AO system of the 4.2-m William Herschel Telescope on La Palma. It delivers an AO-corrected image to a lenslet array at the focal plane of the optical integral-field spectrograph OASIS. The resulting 1100 spectra are imaged onto a high-QE, low-fringing MITLL3 CCD. A range of spectroscopic and spatial (0.09–0.42 arcsec/lenslet) configurations is available. At wavelength  0.7 μm, the NAOMI-corrected FWHM is typically half that of the natural seeing. Scheduled OASIS observing began in semester 2004B, with 9 programmes awarded a total of 26 nights during the first year of operation. A Rayleigh laser guide star is under development, with first light expected summer 2006. In conjunction with NAOMI/OASIS, this will provide a unique facility: AO-corrected optical integral-field spectroscopy anywhere on the northern sky.