The Revised Orbit of the Delta Sco System
  In anticipation of the possible collision between a circumstellar disk and the secondary star in the highly eccentric binary system Delta Scorpii, high angular resolution interferometric observations have been acquired aimed at revising the binary parameters. The Navy Prototype Optical Interferometer (NPOI) was used to spatially resolve the binary components in 2000 and over a period between 2005 and 2010. The interferometric observations are used to obtain the angular separations and orientations of the two stellar components at all epochs for which data has been obtained, including 2005 and 2006, for which based on previous studies there was some uncertainty as to if the signature of binarity can be clearly detected. The results of this study represent the most complete and accurate coverage of the binary orbit of this system to date and allow for the revised timing of the upcoming periastron passage that will occur in 2011 to be obtained. 
C. Tycner (1), A. Ames (1), R. T. Zavala (2), C. A. Hummel (3), J. A.   Benson (2), D. J. Hutter (2) ((1) Central Michigan U...
astro-ph.SR