Interstellar reddening towards six small areas in Puppis-Vela

Context. The line-of-sight towards Puppis-Vela contains some of the most interesting and elusive objects in the solar neighbourhood, including the Gum nebula, the IRAS Vela shell, the Vela SNR, and dozens of cometary globules. Aims. We investigate the distribution of the interstellar dust towards six small volumes of the sky in the region of the Gum nebula. Methods. New high-quality four-colour uvby and Hβ Strömgren photometry obtained for 352 stars in six selected areas of Kapteyn and complemented with data obtained in a previous investigation for two of these areas, were used to estimate the colour excess and distance to these objects. The obtained colour excess versus distance diagrams, complemented with other information, when available, were analysed in order to infer the properties of the interstellar medium permeating the observed volumes. Results. On the basis of the overall standard deviation in the photometric measurements, we estimate that colour excesses and distances are determined with an accuracy of \hbox{$0\fm010$} and better than 30%, respectively, for a sample of 520 stars. A comparison with 37 stars in common with the new Hipparco