Accurate pre- and post-eruption orbital periods for the dwarf/classical nova V1017 Sgr

V1017 Sgr is a classical nova (from 1919) that displayed an earlier dwarf nova eruption (from 1901) and underwent two more dwarf nova events (in 1973 and 1991). Previous work on this bright system in quiescence (V = 13.5) has consisted only of a few isolated magnitudes, a few spectra and an ambiguous claim of an orbital period of 5.714 d based on nine radial velocities. To test this period, we hav...