Systematic uncertainties of broad-band photometries of flux standards

Let's consider the systematic uncertainties of broad-band fluxes of standards. These uncertainties will be used for the chi-square calculations of broad-band SED fitting, in addition to the statistic errors in the broad-band fluxes. Including systematic uncertainties makes the chi-square estimate more robust and relaxes a cut-off of models based on a prior from broad-band SED fitting.

The sources of systematic uncertainties are primarily the flux calibration of photometry and the correction for Galactic extinction. For PS1, the former is about 1-2%. The latter may be larger than the former. The levels of systematic uncertainties depend on specific bands.

We will discuss the systematic uncertainties for each band and incorporate them into the flux calibration procedure for broad-band SED fitting and scaling models to match the observed broad-band fluxes.