Spectropolarimetric observations of Herbig Ae/Be Stars I: HiVIS spectropolarimetric calibration and reduction techniques

TL;DR

This paper details the calibration and data reduction techniques for high-precision spectropolarimetric observations of Herbig Ae/Be stars using the HiVIS instrument, including hardware upgrades and validation with other spectropolarimeters.

Contribution

It introduces new calibration methods, software enhancements, and hardware upgrades for the HiVIS spectropolarimeter, improving measurement accuracy and reliability.

Findings

Successful calibration of the HiVIS instrument for small polarization changes

Verification of HiVIS results through comparison with CFHT ESPaDOnS data

Demonstrated consistency with other spectropolarimeters like ISIS and WW

Abstract

Using the HiVIS spectropolarimeter built for the Haleakala 3.7m AEOS telescope in Hawaii, we are collecting a large number of high precision spectropolarimetrc 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 HD163296. Comparision of this and other HiVIS data with stellar observations from the ISIS and WW spectropolarimeters in the literature further shows the usefulness of this instrument.