MS 0302+17 is a galaxy supercluster located in the constellation Aries at a distance of 4.485 billion light years (lookback time), equivalent to a comoving distance of 5.338 billion light years. The dimensions are around 6 million parsecs.^[1][2]

MS 0302+17 contains three massive galaxy clusters. Of these the first, known as CL 0303+1706 was discovered by Alan Вressler and Jim Gunn, using a conventional optical telescope; it is located along the eastern edge of the supercluster and consists of an important concentration of reddish galaxies. Observations made with the Einstein X-ray Observatory revealed the existence of two other clusters: MS 0302+1659 and MS 0302+1717, which are located near the northern edge of the observation field. The MS prefix derives from Medium Sensitivity because X-ray observations are part of the Einstein Medium Sensitivity Survey.^[3][1] An interesting fact of the survey is a couple of giant arches located near the luminous central galaxies of MS0302+1659, images of remote galaxies enhanced by the gravitational lensing phenomenon created by the supercluster.^[3]