Speckle Interferometry is a technique which utilizes atmospheric wave-front distortions to obtain diffraction-limited resolution of the spatial characteristics of astronomical objects. While the technique is limited in its application to imaging, the astrometric accuracy and precision which can be obtained are very high. The ideal target to take advantage of this technique is the measurement of the relative positions of stars in binary and multiple star systems. In the application of Kepler's Law for the determination of stellar masses the cubic dependence on separation calls for measures of high quality. The program of Speckle Interferometry conducted at the United States Naval Observatory (USNO) has been in operation for over seven years now and regular presentation of these results continues. Careful, spatial calibration results in typical internal errors of 0.5 % in separation and 0.5(deg) in position angle. In addition to this, careful attention is needed to insure that observations are made of common objects with other speckle interferometry groups as well as of objects which can be observed with other techniques in both closer and wider separation regimes. Regular observation of known binary systems is needed to refine orbits, to provide secondary calibration, and to maintain the observational timebase of long period systems for the determination of their orbital parameters at some point in the future. In addition to this observational program, there is also a need to observe targets which may be indicated as possible multiples through other techniques. These indicators might be stepped lunar occultation traces, indications of third light in eclipsing binaries, variable radial velocity determinations, or objects which may be overluminious for their spectral type. The Hipparcos satellite provides many other targets which may have been seen as single but whose astrometric solutions may indicate the presence of another component. Also, to provide good point source calibrators, systems which are assumed to be single should be investigated to provide another check on their multiplicity status.
Bulletin of the American Astronomical Society
- Pub Date:
- January 1998