WASP-12 b, WASP-33 WASP-36 and WASP-46 b are four transiting planetary systems which we have studied. These systems' light curves were derived from observations made by the Transiting Light Exoplanet Survey Satellite (TESS) some ground-based telescopes. We used Exofast-v1 to model these calculate mid-transit times. Also, plotted TTV diagrams for them using times those available within literatur...