Characterization of a dual-beam, dual-camera optical imaging polarimeter. Issue 4 (20th April 2020)

• Record Type: Journal Article
• Authors: Shrestha, Manisha; Steele, Iain A; Piascik, Andrzej S; Jermak, Helen; Smith, Robert J; Copperwheat, Chris M
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 494:Issue 4(2020)
• Page Start: 4676
• Page End: 4686
• Publication Date: 2020-04-20
• Subjects: instrumentation: polarimeters; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa1049
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Polarization plays an important role in various time-domain astrophysics to understand the magnetic fields, geometry, and environments of spatially unresolved variable sources. In this paper we present the results of laboratory and on-sky testing of a novel dual-beam, dual-camera optical imaging polarimeter (MOPTOP) exploiting high sensitivity, low-noise CMOS technology, and designed to monitor variable and transient sources with low systematic errors and high sensitivity. We present a data reduction algorithm that corrects for sensitivity variations between the cameras on a source-by-source basis. Using our data reduction algorithm, we show that our dual-beam, dual-camera technique delivers the benefits of low and stable instrumental polarization (<0.05 per cent for lab data and <0.25 per cent for on sky data) and high throughput while avoiding the additional sky brightness and image overlap problems associated with dual-beam, single-camera polarimeters.