FUSE , HST and SDSS spectra of the cataclysmic variable SDSSJ080908.39 +381406.2 provide a spectral flux distribution from 900–9200Å .
This data set is used to illustrate procedures for calculating and testing system models .
The spectra are not contemporaneous .
The illustrations are based on a system with a 1.0 M _ { \odot } white dwarf , a 0.30 M _ { \odot } , 3500K , Roche lobe-filling secondary star , and an accretion disk extending to the tidal cutoff radius .
Assuming a similar accretion state for the non-simultaneous spectra , the best standard model fit is with a mass transfer rate of 3.0 { \times } 10 ^ { -9 } M _ { \odot } { yr ^ { -1 } } .
Extensive simulations demonstrate that the accretion disk must be truncated at its inner edge if the temperature profile follows the standard model , but truncated models face severe objections , which we address .
Following additional simulation tests , we obtain a model accretion disk with a temperature profile comparable to the profile for SW Sex as determined from tomographic image reconstruction .
This model fits the discovery SDSS spectrum well but has a flux deficit in the UV and FUV .
Emission from a white dwarf is a plausable source of additional flux .
Adding this source to the disk synthetic spectrum produces FUV flux that can explain the observed flux .

An additional ( archival ) SDSS spectrum is fainter by about 0.3 magnitude in the optical .
Additional analysis showed that UV residuals from a model fitting the archival optical wavelength spectrum are unacceptably large .
Contemporaneous spectra from all wavelength regions would be necessary for a reliable system model .
Our discussion illustrates how this conclusion follows from the system models .