  Aims: We test the reliability of the observed and calculated spectral
irradiance variations between 200 and 1600 nm over a time span of three solar
rotations in 2004.
  Methods: We compare our model calculations to spectral irradiance
observations taken with SORCE/SIM, SoHO/VIRGO and UARS/SUSIM. The calculations
assume LTE and are based on the SATIRE (Spectral And Total Irradiance
REconstruction) model. We analyse the variability as a function of wavelength
and present time series in a number of selected wavelength regions covering the
UV to the NIR. We also show the facular and spot contributions to the total
calculated variability.
  Results: In most wavelength regions, the variability agrees well between all
sets of observations and the model calculations. The model does particularly
well between 400 and 1300 nm, but fails below 220 nm as well as for some of the
strong NUV lines. Our calculations clearly show the shift from
faculae-dominated variability in the NUV to spot-dominated variability above
approximately 400 nm. We also discuss some of the remaining problems, such as
the low sensitivity of SUSIM and SORCE for wavelengths between approximately
310 and 350 nm, where currently the model calculations still provide the best
estimates of solar variability.
