All-sky imaging of visible-wavelength atmospheric polarization at Mauna Loa, Hawaii

An all-sky imaging polarimeter was deployed in summer 2008 to the Mauna Loa Observatory in Hawaii to study clear-sky atmospheric skylight polarization. The imager, designed at Montana State University, operates in four wavebands in the visible region and one near infrared (NIR) waveband of the spectrum and has dual field-of-view capability. This paper describes the Mauna Loa deployment and presents comparisons of these data to those observed by Coulson with a principal-plane scanning polarimeter in the late 1970s and early 1980s. We further show how the all-sky imaging technique yields additional insight to the nature of skylight polarization beyond what is observed in a single scan of the solar principal plane.