15.6 Concluding remarks

Mosaic observations are now routinely performed with the Plateau de Bure interferometer, at both $\lambda$ 3 mm and $\lambda$ 1.3 mm. Data processing requires a few more operations than normal observations, but does not present any specific difficulties. Reconstruction and deconvolution algorithms are available in the MAPPING software. The number of mosaics actually observed with the Plateau de Bure interferometer regularly increased during the last years. For the last observing period, it amounts about 40% of the mapping projects (the fraction of observing time used for mosaics is much lower, as many time-consuming detection projects are also performed). The number of fields are usually $\leq 6$, but can be more important in some cases: the largest mosaic observed up to now (September 1998) has 13 fields.