2008PASP..120...89H

Using the High-Resolution Visible Spectrograph (HiVIS) spectropolarimeter built for the Haleakala 3.7 m Advanced Electro-optical System (AEOS) telescope in Hawaii, we are collecting a large number of high precision spectropolarimetric observations of stars. In order to precisely measure very small polarization changes, we have performed a number of polarization calibration techniques on the AEOS telescope and HiVIS spectrograph. We have extended our dedicated IDL reduction package and have performed some hardware upgrades to the instrument. We have also used the ESPaDOnS spectropolarimeter on CFHT to verify the HiVIS results with back-to-back observations of MWC 361 and HD 163296. Comparison of this and other HiVIS data with stellar observations from the Intermediate-dispersion Spectroscopic and Imaging System (ISIS) and William-Wehlau (WW) spectropolarimeters in the literature further shows the usefulness of this instrument.