2021RNAAS...5..148S

For Cataclysmic Variables (CVs), the record of many eclipse times (as presented in the traditional O - C curves) often displays a small-amplitude fast jitter on timescales of under a few years, with these often being interpreted as physical effects such as from third bodies in the system (including planets), or from azimuthal movements of the Hot Spot around the edge of the accretion disk. Recently, with the new and excellent light curves from spacecraft missions TESS and Kepler, we can measure large numbers of eclipse times down to orbit-by-orbit timescales. For four representative CVs (DQ Her, U Sco, RW Tri, and UX UMa), I find that the O - C jitter is constant from one-orbit-to-the-next out to eclipses separated by many years. This demonstrates that the jitter is not caused by physical effects on the orbit, nor by moving Hot Spots. This result was predicted for the expected jitter in eclipse times arising from the ubiquitous flickering in all CV light curves, where random flickers before/after eclipse minima will shift the measured eclipse times later/earlier than the true time of conjunction.