... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... A sample of our new eclipse observations phased on our new ephemeris (section 4.2) Vertical grey bars indicate ingress and egress of the main accretion spot. ... When combined with published eclipse times and archival data spanning тИ®27 years, we detect departures from a linear and quadratic trend of тИ®60 s. The departures are strongly suggestive of two cyclic variations of 16(3) and 5.25(25) years. ...