  We present new warm Spitzer occultation photometry of WASP-26 at 3.6{\mu}m
and 4.5{\mu}m along with new transit photometry taken in the g,r and i bands.
We report the first detection of the occultation of WASP-26b, with occultation
depths at 3.6{\mu}m and 4.5{\mu}m of 0.00126 +/- 0.00013 and 0.00149 +/-
0.00016 corresponding to brightness temperatures of 1825+/-80K and 1725+/-89K,
respectively. We find that the eccentricity of the orbit is consistent with a
circular orbit at the 1{\sigma} level with a 3{\sigma} upper limit of e < 0.04.
According to the activity-inversion relation of Knutson et al. (2010), WASP-26b
is predicted to host a thermal inversion. The brightness temperatures deduced
from the eclipse depths are consistent with an isothermal atmosphere, although
it is within the uncertainties that the planet may host a weak thermal
inversion. The data are equally well fit by atmospheric models with or without
a thermal inversion. We find that variation in activity of solar-like stars
does not change enough over the time-scales of months or years to change the
interpretation of the Knutson et al. (2010) activity-inversion relation,
provided that the measured activity level is averaged over several nights.
Further data are required to fully constrain the thermal structure of the
atmosphere because the planet lies very close to the boundary between
atmospheres with and without a thermal inversion.
