  It has been suggested that diffuse ionized gas can extend all the way to the
end of the HI disc, and even beyond, such as in the case of the warped galaxy
NGC 253 (Bland-Hawthorn et al. 1997). Detecting ionized gas at these radii
could carry significant implications as to the distribution of dark matter in
galaxies. With the aim of detecting this gas, we carried out a deep Halpha
kinematical analysis of two Sculptor group galaxies, NGC 247 and NGC 300. The
Fabry-Perot data were taken at the 36-cm Marseille Telescope in La Silla,
Chile, offering a large field of view. With almost 20 hours of observations for
each galaxy, very faint diffuse emission is detected. Typical emission measures
of 0.1 cm^-6 pc are reached. For NGC 247, emission extending up to a radius
comparable with that of the HI disc (r~13') is found, but no emission is seen
beyond the HI disc. For NGC 300, we detect ionized gas on the entirety of our
field of view (r_max~14'), and find that the bright HII regions are embedded in
a diffuse background. Using the deep data, extended optical rotation curves are
obtained, as well as mass models. These are the most extended optical rotation
curves thus far for these galaxies. We find no evidence suggesting that NGC 247
has a warped disc, and to account for our non detection of Halpha emission
beyond its HI disc, as opposed to the warped galaxy NGC 253, our results favour
the model in which only through a warp, ionization by hot young stars in the
central region of a galaxy can let photons escape and ionize the interstellar
medium in the outer parts.
