We observed two eclipses of the Kepler-13A planetary system , on UT 2014 April 28 and UT 2014 October 13 , in the near-infrared using Wide Field Camera 3 on the Hubble Space Telescope .
By using the nearby binary stars Kepler-13BC as a reference , we were able to create a differential light curve for Kepler-13A that had little of the systematics typically present in HST/WFC3 spectrophotometry .
We measure a broadband ( 1.1 \mu m to 1.65 \mu m ) eclipse depth of 734 \pm 28 ppm , and are able to measure the emission spectrum of the planet at R \approx 50 with an average precision of 70 ppm .
We find that Kepler-13Ab possesses a noninverted , monotonically decreasing vertical temperature profile .
We exclude an isothermal profile and an inverted profile at more than 3 \sigma .
We also find that the dayside emission of Kepler-13Ab appears generally similar to an isolated M7 brown dwarf at a similar effective temperature .
Due to the relatively high mass and surface gravity of Kepler-13Ab , we suggest that the apparent lack of an inversion is due to cold-trap processes in the planet ’ s atmosphere .
Using a toy model for where cold-traps should inhibit inversions , and observations of other planets in this temperature range with measured emission spectra , we argue that with more detailed modeling and more observations we may be able to place useful constraints on the size of condensates on the daysides of hot Jupiters .