PEPPER: polarization-encoding differential photometer and polarimeter

Abstract

ABSTRACT PEPPER is a high-speed dierential Polarization-Encoded Photometer and Polarimeter 1 developed in the Centerfor Astronomical Adaptive Optics at the University of Arizona, Tucson, by Dr. Dan Potter and Matthew Graham.PEPPER is capable of acting as a high-speed polarimeter by using electro-optical switching to chop betweenstandard star and target star, and between in and out-feature bandpass “lter at frequencies fast enough tosuppress atmospheric variations. 2 PEPPER is capable of either high-speed polarimetry or dierential photometryusing a combination of simultaneous imaging and electro-optical switching. In the dierential photometry mode,PEPPER utilizes the electro-optical switching to calibrate instrumental and atmospheric photometric variation.This technique coupled with a zero-read noise photon counting detector achieves photon noise limited resultsdemonstrated to an accuracy of less than 1 part in 10 5 . Herein we present the design concept behind thephotometer and the polarimeter mode of PEPPER, as well as, results from observations in the dierentialphotometer mode at the Steward 90 inch telescope, at the Kitt Peak National Observatory, Tucson, Arizona.Results from the analysis of near IR polarimetry observations of young stars with circumstellar disks taken atthe Gemini North Telescope with the Hokupaa adaptive optics system are also presented.Keywords: PEPPER, circumstellar disks, photometer, polarimeter