Precise photometric transit follow-up observations of five close-in exoplanets: update on their physical properties

Abstract

We report the results of the high-precision photometric follow-up observations of five transiting hot Jupiters, WASP-33b, WASP-50b, WASP-12b, HATS-18b, and HAT-P-36b. The observations are made from the 2 m Himalayan Chandra Telescope at Indian Astronomical Observatory, Hanle, and the 1.3 m J. C. Bhattacharyya Telescope at Vainu Bappu Observatory, Kavalur. This exercise is a part of the capability testing of the two telescopes and their back-end instruments. Leveraging the large aperture of both the telescopes used, the images taken during several nights were used to produce the transit light curves with high photometric signal-to-noise ratio (>200) by performing differential photometry. In order to reduce the fluctuations in the transit light curves due to various sources such as stellar activity, varying sky transparency, etc., we preprocessed them using wavelet denoising and applied a Gaussian process correlated noise modeling technique while modeling the transit light curves. To demonstrate the efficiency of the wavelet denoising process we have also included the results without the denoising process. A state-of-the-art algorithm used for modeling the transit light curves provided the physical parameters of the planets with more precise values than reported earlier.