5 Summary

We have presented optical photometry in the Johnson B and Gunn r bands of the UCM Survey, a local sample of star-forming galaxies. The optical colours of UCM galaxies have been compared with the literature. Though there is a great dispersion in our data, statistically there is a good correlation between multiband photometric, morphological and spectroscopic properties.

Optical colours for the UCM galaxies, when compared with those calculated by Fukugita et al. ([1995]) according to their Hubble type, seem to be slightly bluer in early-type spirals and redder in irregulars and BCD's.

Related to the spectroscopic properties of our galaxies, the calculated colours show the reddening of the objects whose H$\alpha$ emission is associated with the nucleus of the galaxy (SBN or Sy). We have also noticed that, as expected, low metallicity objects seem to be the bluest ones.

In next papers we will study the morphological properties of the UCM sample in the Johnson B band. Using bulge-disk decompositions and H$\alpha$ images we will perform synthesis models and will compare global properties of our sample with the galaxy population at high redshift.

Acknowledgements

This paper is based on observations obtained at the German-Spanish Astronomical Centre, Calar Alto, Spain, operated by the Max-Planck Institut für Astronomie (MPIA), Heidelberg, jointly with the Spanish Commission for Astronomy. It is also partly based on observations made with the Jacobus Kapteyn Telescope operated on the island of La Palma by the Royal Greenwich Observatory in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias and the 1.52 m telescope of the EOCA/OAN Observatory. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We have also use of the LEDA database, http://www-obs.univ-lyon1.fr.

This research was also supported by the Spanish Programa Sectorial de Promoción General del Conocimiento under grants PB96-0610 and PB96-0645.

We would like to thank C.E. García-Dabó and S. Pascual for their help during part of the observing runs.

We are grateful to Dr. M. Fukugita for his helpful remarks that have improved this paper.