  Deep Halpha observations of the Sculptor Group galaxy NGC 7793 were obtained
on the ESO 3.60m and the Marseille 36cm telescopes at La Silla, Chile. Halpha
emission is detected all the way to the edge of the HI disk, making of the HII
disk of NGC 7793 one of the largest ever observed in a quiet non-AGN late-type
system. Even in the very outer parts, the HII ionizing sources are probably
mainly internal (massive stars in the disk) with an unlikely contribution from
the extragalactic ionizing background. The Halpha kinematics confirms what had
already been seen with the HI observations: NGC 7793 has a truly declining
rotation curve. However, the decline is not Keplerian and a dark halo is still
needed to explain the rotation velocities in the outer parts.
