TRANSIT TIMING ANALYSIS AND PARAMETER REFINEMENT OF THE QATAR-1 SYSTEM

In this study, new ground-based transit photometry for Qatar-1b, obtained with the 1.0 m TUG100 telescope in Türkiye, is presented alongside high-precision space-based data from the TESS mission. Using EXOFASTv2, we performed a global MCMC fitting of the light curves to update the physical and orbital configuration of the system. Our results remain consistent with previously published stellar and planetary parameters. To investigate the orbital period variations of the system, we combined our new transit timings with historical and TESS data, allowing us to update the orbital period. An evaluation of the extended O–C diagram suggests that a linear ephemeris is sufficient, as we find no significant evidence (𝛥𝐵𝐼𝐶 = 5.86) for long-term orbital period variations such as orbital decay. Additionally, probing the frequency analysis with both the Lomb-Scargle periodogram and the Weighted Wavelet Z-transform (WWZ) confirmed the absence of any prominent periodic variations.