Observing Circumstellar Neighbourhoods with the Extreme Polarimeter


The study of circumstellar environments at ever higher contrasts has generated considerable interest in recent years. One method to increase the contrast is to observe the linearly polarized light scattered by the circumstellar material while suppressing the unpolarized stellar flux. This paper presents some sample imaging polarimetry results obtained with the Extreme Polarimeter (ExPo). ExPo operates in the visible part of the spectrum, and currently achieves a polarimetric sensitivity of 10$^-4$. Despite the demise of the Utrecht Astronomical Institute, where this instrument was developed, the instrument is still being used and upgraded. It has now moved to the Leiden Observatory.

370 Years of Astronomy in Utrecht