Deep Fabry-Perot HObservations of NGC 7793: a Very Extended HDisk and a Truly Declining Rotation Curve

Deep Hobservations of the Sculptor Group galaxy NGC 7793 were ob- tained on the ESO 3.60m and the Marseille 36cm telescopes at La Silla, Chile. Hemission is detected all the way to the edge of the H I disk, making of the H II 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 H II ionizing sources are probably mainly internal (massive stars in the disk) with an unlikely contribution from the extragalactic ionizing background. The Hkinematics confirms what had already been seen with the H I 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.