A continuous Flaring- to Normal-branch transition in Sco X-1
  We report the first resolved rapid transition from a Flaring Branch Oscillation to a Normal Branch Oscillation in the RXTE data of the Z source Sco X-1. The transition took place on a time scale of ~100 seconds and was clearly associated to the Normal Branch-Flaring Branch vertex in the color-color diagram. We discuss the results in the context of the possible association of the Normal Branch Oscillation with other oscillations known both in Neutron-Star and Black-Hole systems, concentrating on the similarities with the narrow 4-6 Hz oscillations observed at high flux in Black-Hole Candidates. 
Piergiorgio Casella (1 and 2), Tomaso Belloni (1), Luigi Stella (2)   ((1) INAF - Oss. Brera, (2) INAF - Oss. Roma)