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

TL;DR

This paper introduces the design, calibration, and initial observational results of the Dual-Beam Imaging Polarimeter (DBIP) for the UH 88-inch telescope, focusing on measuring polarization of point sources like asteroids.

Contribution

The paper presents a new polarimeter instrument, its calibration process, and initial measurements demonstrating its precision and application to asteroid polarization studies.

Findings

Achieved 0.03% polarization measurement precision

Confirmed asteroid Psyche's negative polarization of -1.037%

Found no significant polarization modulation with asteroid rotation

Abstract

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 2048x2048 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.