AAVSO: American Association of Variable Star Observers

An Array Photo-Polarimeter for Blazar Measurements (Abstract)

Volume 48 number 2 (2020)

Gary M. Cole
Starphysics Observatory, Reno, NV, and Visiting Scholar, UC San Diego Center for Astrophysics and Space Sciences; garycole@mac.com
Andrew Friedman
Assistant Research Scientist, UC San Diego Center for Astrophysics and Space Sciences; asf@ucsd.edu


(Abstract only) This paper describes the ongoing development of an automated array of small telescopes (APPOL) for the multicolor, time series measurement of polarized light from Blazars and similar cosmological sources. At 14th magnitude and below, and often exhibiting rapid variation, these objects are challenging polarimetric targets with relatively few published multicolor observations. The observing system is distributed across two piers located 2 m apart. It contains two 35-cm optical telescopes equipped with self-guiding dual beam polarimeters and two 20-cm co-mounted photometric imagers. These are supplemented with instruments to measure the polarization, brightness, clarity, and spectra of the target sky region. Observations can be made across the optical spectrum from 400 nm to 900 nm. Target acquisition, data reduction, and the time synchronized operation of 12 cameras is coordinated by a custom software system. One of the polarimeters features a novel optical assembly that provides simultaneous two-color dual beam polarimetry within a single imager. This technique may also be useful for two color photometry of transient objects. This work has been done in conjunction with the Ax Center for Experimental Cosmology at UCSD. It is envisioned as a pathfinder experiment for a future large telescope test of Lorenz Invariance across cosmological distances. APPOL achieved first light in late 2017. The first paper based upon this work appeared in Physical Review D in early 2019.