The presence of dust in starburst galaxies complicates the study of their
stellar populations as the dust's effects are similar to those associated with
changes in the galaxies' stellar age and metallicity. This degeneracy can be
overcome for starburst galaxies if UV/optical/near-infrared observations are
combined with far-infrared observations. We present the calibration of the flux
ratio method for calculating the dust attenuation at a particular wavelength,
Att(\lambda), based on the measurement of F(IR)/F(\lambda) flux ratio. Our
calibration is based on spectral energy distributions (SEDs) from the PEGASE
stellar evolutionary synthesis model and the effects of dust (absorption and
scattering) as calculated from our Monte Carlo radiative transfer model. We
tested the attenuations predicted from this method for the Balmer emission
lines of a sample starburst galaxies against those calculated using radio
observations and found good agreement. The UV attenuation curves for a handful
of starburst galaxies were calculated using the flux ratio method, and they
compare favorably with past work. The relationship between Att(\lambda) and
F(IR)/F(\lambda) is almost completely independent of the assumed dust
properties (grain type, distribution, and clumpiness). For the UV, the
relationship is also independent of the assumed stellar properties (age,
metallicity, etc) accept for the case of very old burst populations. However at
longer wavelengths, the relationship is dependent on the assumed stellar
properties.Comment: accepted by the ApJ, 18 pages, color figures, b/w version at
http://mips.as.arizona.edu/~kgordon/papers/fr_method.htm