ZetaPersei: a package for polarimetric astronomical observations and instrument calibration

ZetaPersei is a software package designed to aid astronomical polarimetric observation planning. The goal of the package is to harness standard star catalogs and provide quantitative errors on instrument calibration matrices. We present an interface that searches existing catalogs of unpolarized and polarized standards for astronomical and solar system targets within a certain on-sky distance. To determine the required on-sky SNR to achieve a certain accuracy in an instrumental polarization model, we present an analytical formulation to calculate the covariance matrix of the instrument Mueller matrix parameters from the SNR of two standard stars. This calculation is generalized for all dual channel polarimeters with rotators that allow for modulation between Stokes Q and U and is applicable for any overdetermined linear system with multiple Stokes I measurements. With the tools for finding standards and calculating instrument Mueller matrix coefficient SNRs, ZetaPersei can help with planning astronomical observations on any polarimeter.