A neutral hydrogen study of the galaxy NGC 5236.

Summary. The Sc galaxy NGC 5236 has been observed in the 21-cm hydrogen line with the Nancay radio telescope. An asymmetry in the H 1 distribution is found: there is 20 % more H i to the South of the optical centre than to the North and the Hi centre of mass is displaced 5' towards the South with respect to the optical one. The major axis of the neutral hydrogen distribution (PA =00) appears quite different from the optical one (PA =450) The study of the velocity field shows that the kinematical major axis position angle varies from 450 to 0 as one considers more and more external regions in the galaxy. The H I centre may be taken as the kinematical centre. Non-circular motions are superimposed on a circular rotation. The integral parameters of NGC 5236 appear to be quite normal for its morphological type. Key words: galaxies - neutral hydrogen distribution - 21-cm line radiation