Full Orbital Phase Curve of KELT-1b using TESS observations

We present our joint model for comprehensive phase curve analysis of the transiting brown dwarf KELT-1b using observations from the Transiting Exoplanet Survey Satellite (TESS). We developed a full model of the phase curve over the orbit of a star-planet system, which includes primary transit, secondary eclipse, thermal emission, reflection, ellipsoidal tidal distortion, and Doppler beaming. All of these are jointly fitted simultaneously to obtain the parameters from the data sets. After taking out the instrumental systematic noise, we reliably detect the secondary eclipse with a depth of 383 +36 −24 ppm. Its hotspot is located east of the substellar point, demonstrating heat transport from the dayside (3005 +207 −191 K) to the nightside (< 1491 +162 −145 K) at the altitudes probed by TESS. Our estimated geometric albedo, Ag = 0.47 +0.06 −0.04 , suggests that KELT-1b has a high geometric albedo. Finally, our estimated amplitude of the ellipsoidal variation and Doppler beaming signal is in agreement with the predictions of the theoretical expectations.