The VVDS Data‐Reduction Pipeline: Introducing VIPGI, the VIMOS Interactive Pipeline and Graphical Interface

The VIMOS VLT Deep Survey (VVDS), designed to measure 150,000 galaxy redshifts, requires a dedicated data reduction and analysis pipeline to process in a timely fashion the large amount of spectroscopic data being produced. This requirement has lead to the development of the VIMOS Interactive Pipeline and Graphical Interface (VIPGI), a new software package designed to simplify to a very high degree the task of reducing astronomical data obtained with VIMOS (Visible Multi–Object Spectrograph), the imaging spectrograph built by the VIRMOS Consortium for the European Southern Observatory and mounted on Unit 3 (Melipal) of the VLT (Very Large Telescope) at Paranal Observatory (Chile). VIPGI provides the astronomer with specially designed VIMOS data‐reduction functions, a VIMOS‐centric data organizer, and dedicated data browsing and plotting tools, which can be used to verify the quality and accuracy of the various stages of the data‐reduction process. The quality and accuracy of the data‐reduction pipeline are comparable to those obtained using well‐known IRAF tasks, but the speed of the data‐reduction process is significantly increased, because of the dedicated nature of VIPGI. In this paper we discuss the details of the multiobject spectroscopy (MOS) data‐reduction pipeline that has been implemented in VIPGI, as applied to the reduction of some 20,000 VVDS spectra, quantitatively assessing the accuracy of the various reduction steps. We also provide a more general overview of VIPGI capabilities, a tool that can be used for the reduction of any kind of VIMOS data.