  In this paper I show that the concept of relativistic beaming -- the process
by which light emitted by a fast moving sources is lensed towards the direction
of motion -- can be easily extended to model the signal from both the star and
any secondary companions. Most companions will be cooler and less massive than
their host star. Their lower mass leads to faster orbital velocities, and thus
a potentially larger beaming effect. The lower temperature will mean that most
of their light is emitted at longer wavelengths, where the relative photometric
dominance of the primary is reduced. Thus for some systems, the secondary
companion can be the main contributor to observed relativistic beaming signals
at long wavelengths. Furthermore, if the system is observed over a range of
wavelengths we can independently constrain the temperature of the companion,
and the mass and radius ratio of the binary. To conclude I discuss the current
and future observational prospects of this signal, using the properties of
known exoplanets to show that such a signal may be observable by upcoming
surveys.
