1995PASP..107..299M

Speckle interferometry has for the past two decades provided a means to measure very accurate relative positions of binary stars, data crucial to the fundamental determination of basic stellar parameters. As a technique for observing small angular separations speckle interferometry is exceeded only by long baseline interferometry (a technique still in infancy) and the observation of lunar occultation phenomena.

As the moon passes in front of stars the light coming from those stars is occulted. Occultations of binary stars can determine relative intensities and can measure separations which are comparable to those measured by long-baseline interferometers. The data are difficult to interpret since the measured separation is a projection of the true angular separation and non-standard filters are often used.

No complete listing of all occultation measures has been published since the compilation of David Evans (IAU Colloquium No. 62, Current Techniques in Double and Multiple Star Research, Lowell Observatory Bulletin No. 167, 1981, eds. Harrington, R.A. & Franz, O.G., Lowell Observatory, Flagstaff). The dissertation presents 772 measures of 357 systems, an increase of 60% over the Evans catalog.

The methodology of speckle interferometry is presented, followed by 362 re-reduction measures and 253 new measures. The re-reduction measures were cases where prior analysis showed no companion. With improved reduction algorithms, detection frequency significantly increased. One observation in eight previously showing no companion produced a measurable result.
Result. were obtained with the 1.8-m Perkins telescope of Lowell Observatory, the 2.5-m Hooker telescope of Mt. Wilson Observatory, the 3.8-m Mayall telescope of Kitt Peak National Observatory and the 4.0-m telescope at Cerro Tololo InterAmerican Observatory.

All but 130 of the occultation objects have speckle observations. The likelihood of future detection by speckle is considered. An analysis of 131 negative results is presented. Of the remaining 96 systems, 66 have been detected by speckle interferometry, 13 for the first time, and 17 new orbits have been calculated. Of these orbits, five (HR 793 = Bla Aa, ADS 3608 = A 1844, HR 3880 = McA 34, HR 5652 = B 2531 Aa, HR 7776 = β Cap) have improved elements over previous orbit calculations, four (BD+24 1805 = Cou 929, ADS 17052 = A 2700, HR 9041 = Fin 359, ADS 17111 = A 2100) have previous but significantly different orbits, five (HR 132 = McA 1 Aa, HR 1808 = McA 19 Aa, HR 2343 = Btz Aa, HR 8060 = Fin 328, HR 8704 = McA 73) are first orbits, and three (HR 763 = McA 7, HR 2130 = McA 24, HR 2846 = McA 30 Aa) are first orbits of spectroscopic binaries.

The occultation catalog, speckle measures, and new orbits will be presented in subsequent CHARA publications.

The detection of occultation binaries by speckle interferometry seems to be predictable, however, there appear to be a small sample of occultation binaries which cannot be detected. These may be spurious. Lunar occultation measures place a good limit on Δm for speckle of about 3.0. CHARA hopes to complete a survey of all occultation objects with current scheduled runs which should result in a further five to ten objects resolved for the first time. While the rate of occultation measures has dropped significantly, they are still continuing to provide useful complementary data for other binary star methods.