Commissioning of the Dual-Beam Imaging Polarimeter for the UH 88-inch telescope

In this paper we present the design, calibration method, and initial results of the Dual-Beam Imaging Polarimeter (DBIP). This new instrument is designed to measure the optical polarization properties of point sources, in particular Main Belt asteroids. This instrument interfaces between the Tek 2048× 2048 camera and the University of Hawaii’s 88-inch telescope, and is available for facility use. Using DBIP we are able to measure linear polarization with a 1-sigma Poisson signal noise of 0.03% per measurement and a systematic error of order 0.06%±0.02%. Additionally, we discuss measurements of the polarization of the asteroid 16 Psyche which were taken as part of the instrument commissioning. We confirm Psyche’s negative polarization of −1.037% ± 0.006% but find no significant modulation of the signal with rotation above the 0.05% polarization level. Subject headings: Astronomical Instrumentation