Commissioning and performances of the VLT-VIMOS

摘要

The Visible Multi-Object Spectrograph VIMOS is a wide field survey instrument in the process of being commissioned for operations at the ESO-VLT. During the first commissioning period, the instrument has confirmed its excellent performances in its three basic modes of operation: direct imaging, multi-slit spectroscopy, and integral field spectroscopy. VIMOS provides the largest imaging field at the VLT with 224 arcmin~2. It offers an unprecedented multiplex gain in multi-slit spectroscopy, with on order 800 slits which can be observed simultaneously. The integral field unit has a field up to 54x54 arcsec~2, with 6400 spectra recorded at once. The overall efficiency of VIMOS combined to the Melipal unit #3 is confirmed to be as computed on the basis of the measured transmission of optical elements. Image quality is confirmed to be excellent, providing images limited by natural seeing in most conditions. High quality slit masks cut by the laser machine coupled to excellent geometric mask to CCD mapping lead to multi-slit spectra of excellent quality. VIMOS is expected to be offered to the ESO community for reguglar observations in early 2003.