  Our goal is to test the feasibility to obtain accurate measurements of the
continuum polarization from high-resolution spectra using the
spectropolarimetric mode of ESPaDOnS. We used the new pipeline OPERA to reduce
recent and archived ESPaDOnS data. A couple of standard polarization stars and
several science objects were tested for the linear mode. In addition, the
circular mode was tested using several objects from the archive with expected
null polarization. Synthetic broad-band polarization was computed from the
ESPaDOnS continuum polarization spectra and compared with published values
(when available) to quantify the accuracy of the instrument. The continuum
linear polarization measured by ESPaDOnS is consistent with broad-band
polarimetry measurements available in the literature. The accuracy in the
degree of linear polarization is around 0.2-0.3% considering the full sample.
The accuracy in polarization position angle using the most polarized objects is
better than 5deg. Consistent with this, the instrumental polarization computed
for the circular continuum polarization is also between 0.2-0.3%. Our results
suggest that measurements of the continuum polarization using ESPaDOnS are
viable and can be used to study many astrophysical objects.
