  Measured rotational speeds of giant planets and brown dwarfs frequently
constitute appreciable fractions of the breakup limit, resulting in centrifugal
expansion of these objects at the equator. According to models of internal
energy transport, this expansion ought to make the poles of a rotator
significantly hotter than the equator, so that inclination of the rotational
axis greatly affects both spectral shape and total flux. In this article, we
explore the dependence of a substellar object's observables on its rotational
speed and axis inclination. To do so, we combine PICASO (a Planetary Intensity
Code for Atmospheric Spectroscopy Observations) with software PARS (Paint the
Atmospheres of Rotating Stars). The former computer program models radiative
transfer within plane-parallel planetary atmospheres, while the latter computes
disk-integrated spectra of centrifugally deformed gaseous masses. We find that
the specific flux of a typical fast-rotating brown dwarf can increase by as
much as a factor of 1.5 with movement from an equator-on to a pole-on view. On
the other hand, the distinctive effect of rotation on spectral shape increases
toward the equator-on view. The latter effect also increases with lower
effective temperature. The bolometric luminosity estimate for a typical fast
rotator at extreme inclinations has to be adjusted by as much as about 20% due
to the anisotropy of the object's observed flux. We provide a general formula
for the calculation of the corresponding adjustment factor in terms of
rotational speed and inclination.

Earth and Planetary Astrophysics;Solar and Stellar Astrophysics