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We present observations of seven transits and seven eclipses of thetransiting planet system HD 189733 taken with Spitzer IRAC at 8 microns. We usea new correction for the detector ramp variation with a double-exponentialfunction. Our main findings are: (1) an upper limit on the variability of theday-side planet flux of 2.7% (68% confidence); (2) the most precise set oftransit times measured for a transiting planet, with an average accuracy of 3seconds; (3) a lack of transit-timing variations, excluding the presence ofsecond planets in this system above 20% of the mass of Mars in low-ordermean-motion resonance at 95% confidence; (4) a confirmation of the planet'sphase variation, finding the night side is 64% as bright as the day side, aswell as an upper limit on the night-side variability of 17% (68% confidence);(5) a better correction for stellar variability at 8 micron causing the phasefunction to peak 3.5 hrs before secondary eclipse, confirming that theadvection and radiation timescales are comparable at the 8 micron photosphere;(6) variation in the depth of transit, which possibly implies variations in thesurface brightness of the portion of the star occulted by the planet, posing afundamental limit on non-simultaneous multi-wavelength transit absorptionmeasurements of planet atmospheres; (7) a measurement of the infraredlimb-darkening of the star, in agreement with stellar atmosphere models; (8) anoffset in the times of secondary eclipse of 69 sec, which is mostly accountedfor by a 31 sec light travel time delay and 33 sec delay due to the shift ofingress and egress by the planet hot spot; this confirms that the phasevariation is due to an offset hot spot on the planet; (9) a retraction of theclaimed eccentricity of this system due to the offset of secondary eclipse; and(10) high precision measurements of the parameters of this system.

The climate of HD 189733b from fourteen transits and eclipses measured by Spitzer