The HPOL spectropolarimeter is a modified Boller and Chivens small telescope spectrograph. The system provides simultaneous spectrophotometry and spectropolarimetry over the range of 3200Å to 10500Å (prior to 1995, the spectral range was 3200Å to 7750Å), with a spectral resolution of 10Å (25Å prior to 1995). The halfwave plate is a super-achromatic half-wave retarder. The wave plate is rotated by a stepper motor and rack and pinion drive, with stops every 11.25 degrees. A Wollaston prism produces two orthogonally polarized beams (ordinary and extraordinary) separated perpendicular to the dispersion. The ultraviolet achromatic camera is specifically designed for this instrument. The camera is all-refractive, which eliminates vignetting and thus enhances the polarimetric stability. The image is focused on a 400 X 1200 pixel CCD. The instrument is installed on one of two telescopes. Primarily, it is installed as a dedicated instrument to the 36" telescope at the University of Wisconsin-Madison Pine Bluff Observatory (PBO). HPOL can also be mounted on the 3.5 m WIYN telescope at Kitt Peak National Observatory for limited observational runs once a year or so.
MAST is archiving these data as a complement to the data obtained by the WUPPE instrument flown on the Space Shuttle as part of the ASTRO project that is also archived as MAST.