 Dumusque used a variety of mathematical transformations to isolate the planet's gravitational signal and remove the surrounding stellar noise.The transformations filtered out other sources of radial-velocity variance, including effects of starspots, photospheric granulation and rotation, as well as interference from the neighboring star Alpha Centauri A.The final, derived radial-velocity measurements showed the periodic influence of the planet on the star, but were near the threshold of the HARPS instrument's sensory capabilities.