Millisecond Dips in Sco X-1 are Likely the Result of High-Energy   Particle Events
  Chang et al. (2006) reported millisecond duration dips in the X-ray intensity of Sco X-1 and attributed them to occultations of the source by small trans-Neptunian objects (TNOs). We have found evidence that these dips are in fact not astronomical in origin, but rather the result of high-energy charged particle events in the RXTE PCA detectors. 
T. A. Jones, A. M. Levine, E. H. Morgan, and S. Rappaport