P3D: a general data-reduction tool for fiber-fed integral-field spectrographs

The reduction of integral-field spectrograph (IFS) data is demanding work. Many repetitive operations are required to convert raw data into, typically, a large number of spectra. This effort can be markedly simplified through the use of a tool or pipeline, which is designed to complete many of the repetitive operations without human interaction. Here we present our semi-automatic data-reduction tool p3d, which is designed to be used with fiber-fed IFSs. Important components of p3d include a novel algorithm for automatic finding and tracing of spectra on the detector and two methods of optimal spectrum extraction in addition to standard aperture extraction. p3d also provides tools to combine several images, perform wavelength calibration and flat field data. p3d is at the moment configured for four IFSs. To evaluate its performance, we tested the different components of the tool. For these tests we used both simulated and observational data. We demonstrate that a correction for so-called cross-talk due to overlapping spectra on the detector is required for three of the IFSs. Without such a correction, spectra will be inaccurate, in particular if there is a significant intensity gradient across the object. Our tests showed that p3d is able to produce accurate results. p3d is a highly general and freely available tool. It is easily extended to include improved algorithms, new visualization tools, and support for additional instruments. The program code can be downloaded from the p3d-project web site http://p3d.sourceforge.net.