Low mass X-ray binaries are double star systems consisting of a low-mass object (such as a Sun-like star or a white dwarf) in orbit around and a neutron star or black hole, as depicted in this artist's representation by M. Weiss (CXC). If one of the companions is indeed a neutron star, then under the right conditions one might expect to observe pulsations: this was the subject of a project undertaken at McGill by Rim Dib and Scott Ransom to search through archival X-ray data for evidence of pulsations in the LMXB 4U 1820-30. An RXTE Archival Search for Coherent X-ray Pulsations in LMXB 4U 1820-30. R. Dib, S. M. Ransom, P. S. Ray, V. M. Kaspi & A. M. Archibald 2005, ApJ, 626, 333