WASP-8b has 2.18 times Jupiter's mass and is on an eccentric (e=0.31) 8.16-day orbit. With a time-averaged equilibrium temperature of 948 K, it is one of the least-irradiated hot Jupiters observed with the Spitzer Space Telescope. We have analyzed six photometric light curves of WASP-8b during secondary eclipse observed in the 3.6, 4.5, and 8.0 Infrared Array Camera bands. The eclipse depths are 0.113± 0.018 0.093± 0.023 1552, 1131, and 938 K. We characterized the atmospheric thermal profile

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... composition of the planet using a line-by-line radiative transfer code and a Markov-chain Monte Carlo sampler. The data indicated no thermal inversion, independently of any assumption about chemical composition. We noted an anomalously high 3.6- brightness temperature (1552 K); by modeling the eccentricity-caused thermal variation, we found that this temperature is plausible for radiative time scales less than ∼ 10^2 hours. However, as no model spectra fit all three data points well, the temperature discrepancy remains as an open question.