  We discuss the transformation of observed photometry into flux for the
creation of spectral energy distributions and the computation of bolometric
luminosities. We do this in the context of supernova studies, particularly as
observed with the Swift spacecraft, but the concepts and techniques should be
applicable to many other types of sources and wavelength regimes. Traditional
methods of converting observed magnitudes to flux densities are not very
accurate when applied to UV photometry. Common methods for extinction and the
integration of pseudo-bolometric fluxes can also lead to inaccurate results.
The sources of inaccuracy, though, also apply to other wavelengths. Because of
the complicated nature of translating broad-band photometry into monochromatic
flux densities, comparison between observed photometry and a spectroscopic
model is best done by comparing in the natural units of the observations. We
recommend that integrated flux measurements be made using a spectrum or
spectral energy distribution which is consistent with the multi-band photometry
rather than converting individual photometric measurements to flux densities,
linearly interpolating between the points, and integrating. We also highlight
some specific areas where the UV flux can be mischaracterized.
