  We investigate the effect of dust on the observed rotation rate of a stellar
bar. The only direct way to measure this quantity relies on the Tremaine &
Weinberg method which requires that the tracer satisfies the continuity
equation. Thus it has been applied largely to early-type barred galaxies. We
show using numerical simulations of barred galaxies that dust attenuation
factors typically found in these systems change the observed bar pattern speed
by 20-40 percent. We also address the effect of star formation on the TW method
and find that it does not change the results significantly. The results
presented here suggest that applications of the TW method can be extended to
include barred galaxies covering the full range of Hubble type.
