6 Summary and conclusion

We present H$\alpha$+[NII] imaging data (fluxes and equivalent widths) of 30 Virgo galaxies obtained at the 2.5 m INT and at the 2.56 m NOT telescopes at El Roque de los Muchachos, La Palma. The present observations of BCD galaxies in the Virgo cluster are aimed at completing at low luminosity a large project of multifrequency observations of galaxies spanning a large range in morphological type and luminosity and belonging to different environments (cluster-isolated) for the purpose of constructing a large data-set suitable for statistical studies.

Acknowledgements

We wish to thank the night operators for their assistance during the observations. This project is partly financed by the French PNG. The data presented here have been taken using ALFOSC, which is owned by the Instituto de Astrofisica de Andalucia (IAA) and operated at the Nordic Optical Telescope under agreement between IAA and the NBIfAFG of the Astronomical Observatory of Copenhagen. We thank L. Cortese for helping us in cros-calibrating photometric observations with spectroscopic data.