  Methods to measure masses of PG1159 stars in order to test evolutionary
scenarios are currently based on spectroscopic masses or asteroseismological
mass determinations. SDSSJ212531.92-010745.9, a recently discovered PG1159 star
in a close binary system, may finally allow the first dynamical mass
determination, and has so far been analysed on the basis of one SDSS spectrum
and photometric monitoring.
  In order to be able to phase radial velocity measurements of the system
SDSSJ212531.92-010745.9, we have followed up the photometric monitoring of this
system. New white light time series of the brightness variation of
SDSSJ212531.92-010745.9 with the Tuebingen 80cm and Goettingen 50cm telescopes
extend the monitoring into a second season (2006). We give the improved
ephemeris for the orbital motion of the system, based on a sine fit which now
results in a period of 6.95573(5)h.
  In 2007, we have obtained a series of phase-resolved medium-resolution
spectra with the TWIN spectrograph at the 3.5m telescope at Calar Alto, which
will allow us to derive the radial velocity curves for both components of the
system, and to perform spectral analyses of the irradiating and irradiated
components at different phases. We briefly describe the newly obtained spectra.
The light curve and radial velocities combined will allow us to carry out a
mass determination.
