WASP-18b Secondary Eclipses Revisited Using TESS Observation.

We report the characterization of a transiting hot Jupiter WASP-18b at optical wavelengths measured by the transiting exoplanet survey satellite (TESS). We analyze the publicly available data collected by the TESS in sector 2. Here, we model the systematic noise using Gaussian processes (GPs) and fit it to the data using the Markov Chain Monte Carlo (MCMC) method. Modelling the TESS light curve returns a planet-to-star radius ratio, p = 0.098010 − 0.000346 + 0.000368 and secondary eclipse depth of 354 − 10 + 11 part-per-million (ppm). The transit ephemeris of WASP-18b is updated using the MCMC method. Finally, we use updated ephemeris to look for transit time variations (TTVs) for WASP-18b to complement our study. We find a quite small deviation of transit timings from a linear ephemeris, which is statistically insignificant. [ABSTRACT FROM AUTHOR]