Extended ionized nebulosities in the galaxies MK 1, MK 3, MK 348 and the quasar 4C 37.43.

The authors present long slit spectroscopic data of three Markarian galaxies and one QSO in the Hβ-[O III] λλ4959 - 5007 wavelength range. They have detected ionized nebulosities around the four objects. They present kinematic data, together with the variations of the [O III] λ5007 line intensity and [O III] λ5007/Hβ intensity ratio throughout the ionized region. The absolute density and filling factor of the ionized gas have been estimated for the four objects studied here and four additional nebulosities previously known. The filling factors are always small. However they tend to be larger in galaxies with weaker UV sources and at smaller distances from the nucleus. A more homogeneous distribution of the gas might also be linked to large turbulent motions.