duchamp: a 3D source finder for spectral-line data

This paper describes the duchamp source finder, a piece of software designed to find and describe sources in three-dimensional, spectral-line data cubes. duchamp has been developed with H i (neutral hydrogen) observations in mind, but is widely applicable to many types of astronomical images. It features efficient source detection and handling methods, noise suppression via smoothing or multi-resolution wavelet reconstruction, and a range of graphical and text-based outputs to allow the user to understand the detections. This paper details some of the key algorithms used and illustrates the effectiveness of the finder on different data sets.