Dynamics of blue compact galaxies, as revealed by their Hα velocity fields^*,**

I. The data, velocity fields and rotation curves

¹ Astronomiska observatoriet, Box 515, S-75120 Uppsala, Sweden
² IGRAP, Observatoire de Marseille, 2 place le Verrier, F-13248 Marseille Cedex 04, France
³ Instituto de Astrofisica de Andalucia, CSIC, Apdo. 3004, E-18080 Granada, Spain

Send offprint request to: G. Östlin, e-mail: ostlin@iap.fr

Received: 10 July 1998
Accepted: 4 December 1998

Abstract

Observations of six luminous blue compact galaxies (BCGs) and two star forming companion galaxies were carried out with the CIGALE scanning Fabry-Perot interferometer attached to the ESO 3.6 m telescope on La Silla. The observations were made in the Hα emission line which is prominent in BCGs. A velocity sampling of 5 km s^-1 and a pixel size of 0.9 arcseconds were used. In this paper we present the observations and the data together with the velocity fields and the derived rotation curves. In addition we provide rough estimates of the total dynamical mass and of the ionised gas mass for each galaxy. All galaxies display rotation, but while the companion galaxies have regular velocity fields, those of the BCGs are complex and appear perturbed. This is the most extensive study to date of the optical velocity fields of BCGs. The interpretation of these results will be presented in a forthcoming paper (Paper II).