#### An important subset: The zero spacing

An important subset of the pseudo-visibility method is the production of only the zero spacing. Indeed, the zero spacing is just the total flux of the observed field-of-view. Hence, if the observed field-of-view is small enough to fit in the single-dish beam (this is in particular always the case if ), a single spectra observed with the single-dish telescope in the direction of the interferometer phase center may be used as zero spacing, only a scaling from Kelvin to Jansky is needed. This is the poor man's solution as only part of the short spacing information is recovered by this technique.