New UBVRI colour distributions in E-type galaxies ^*,**

I. The data

¹ Instituto de Astronomia, Geofisica e Ciências Atmosféricas, Depto. de Astronomia, Universidade de São Paulo, Av. Miguel Stefano, 4200-CEP, 04301-904 S. Paulo, SP-Brazil e-mail: thais@iagusp.usp.br
² Observatoire de Paris, LERMA, 77 Av. Denfert-Rochereau, 75015 Paris, France e-mail: Raymond.Michard@obspm.fr
³ Observatoire de la Côte d'Azur, Département Augustin Fresnel, BP 4229, 06304 Nice Cedex 4, France e-mail: pacheco@obs-nice.fr

Corresponding author: R. Michard, michard@obspm.fr

Received: 17 September 2001
Accepted: 7 November 2001

Abstract

New colour distributions have been derived from wide field UBVRI frames for 36 northern bright elliptical galaxies and a few lenticulars. The classical linear representations of colours against were derived, with some improvements in the accuracy of the zero point colours and of the gradients. The radial range of significant measurements was enlarged both towards the galaxy center and towards the outskirts of each object. Thus, the “central colours”, integrated within a radius of 3´´, and the “outermost colours” averaged near the surface brightness could also be obtained. Some typical deviations of colour profiles from linearity are described. Colour-colour relations of interest are presented. Very tight correlations are found between the colour and the Mg₂ line-index, measured either at the Galaxian center or at the effective radius.