  We present Roche tomograms of the G5-G8 IV/V secondary star in the
long-period cataclysmic variable BV Cen reconstructed from MIKE echelle data
taken on the Magellan Clay 6.5-m telescope. The tomograms show the presence of
a number of large, cool starspots on BV Cen for the first time. In particular,
we find a large high-latitude spot which is deflected from the rotational axis
in the same direction as seen on the K3-K5 IV/V secondary star in the
cataclysmic variable AE Aqr. BV Cen also shows a similar relative paucity of
spots at latitudes between 40-50 degrees when compared with AE Aqr.
Furthermore, we find evidence for an increased spot coverage around longitudes
facing the white dwarf which supports models invoking starspots at the L1 point
to explain the low-states observed in some cataclysmic variables. In total, we
estimate that some 25 per cent of the northern hemisphere of BV Cen is spotted.
  We also find evidence for a faint, narrow, transient emission line with
characteristics reminiscent of the peculiar low-velocity emission features
observed in some outbursting dwarf novae. We interpret this feature as a
slingshot prominence from the secondary star and derive a maximum source size
of 75,000 km and a minimum altitude of 160,000 km above the orbital plane for
the prominence.
  The entropy landscape technique was applied to determine the system
parameters of BV Cen. We find M_1 = 1.18 (+0.28 -0.16) Msolar, M_2 = 1.05
(+0.23 -0.14) Msolar and an orbital inclination of i = 53 degrees +- 4 degrees
at an optimal systemic velocity of \gamma = -22.3 km s-1. Finally, we also
report on the previously unknown binarity of the G5IV star HD 220492.
