Fourth Catalog of Interferometric Measurements of Binary Stars -
Catalog Statistics

Figure 1: Distribution of measures with time. Not included in this figure are nearly 70,000 observations from Hipparcos and Tycho. These data were excluded from the figure in order to avoid a large data "spike" in 1991 which would render the figure of marginal worth. Barely visible are the 1895 observations of Schwarzschild & Villiger (1896), followed two decades later by the 1919-1921 data obtained using the famous 20-foot beam interferometer with the Mount Wilson 100-inch Hooker Telescope by Anderson (1920) and Merrill (1922).

Figure 2: Distribution of measures with separation. The major item to note here is the contribution made at the smallest separation regime (under 0".1) both by long-baseline interferometers and by occultation techniques. This figure clearly indicates that occultation timings could play an important role in binary star astrometry and photometry with greater coordination of observing efforts (to overcome the limitation of one-dimensional coverage) and through the use of standard filters. Unfortunately Figure 1 illustrates a steady decline in published occultation results.

Figure 3: Distribution of interferometric measures with declination. Historically, interferometric observations have mostly been restricted to equipment in the Northern Hemisphere, although this disparity has been reduced somewhat by Hipparcos and Tycho, by the CHARA southern speckle program from 1989-1996, and by the more recent speckle efforts of Horch et al. and the USNO speckle group. A large-scale dedicated interferometric observing program for the Southern Hemisphere is still sorely needed, however.