  3C 273 is an intensively monitored flat-spectrum radio quasar with both a
beamed jet and blue bump together with broad emission lines. The coexistence of
the comparably prominent jet and accretion disk leads to complicated
variability properties. Recent reverberation mapping monitoring for 3C 273
revealed that the optical continuum shows a distinct long-term trend that does
not have a corresponding echo in the Hbeta fluxes. We compile multi-wavelength
monitoring data from the Swift archive and other ground-based programs and
clearly find two components of emissions at optical wavelength. One component
stems from the accretion disk itself and the other component can be ascribed to
the jet contribution, which also naturally accounts for the non-echoed trend in
reverberation mapping data. We develop an approach to decouple the optical
emissions from the jet and accretion disk in 3C 273 with the aid of
multi-wavelength monitoring data. By assuming the disk emission has a
negligible polarization in consideration of the low inclination of the jet, the
results show that the jet contributes a fraction of ~10% at the minimum and up
to ~40% at the maximum to the total optical emissions. This is the first time
to provide a physical interpretation to the "detrending" manipulation
conventionally adopted in reverberation mapping analysis. Our work also
illustrates the importance of appropriately analyzing variability properties in
cases of coexisting jets and accretion disks.
