SIMBAD references

Position angles and separations resulting from 2578 speckle interferometric observations of 590 binary stars are tabulated. This is the third in a series of papers presenting measures obtained using the 66 cm refractor at the US Naval Observatory in Washington, DC, and covers the period from 1995 June through 1996 December. Program stars range in separation from 0".2 to 4".3, with a limiting magnitude of V=11. Random errors are estimated to be 17.0 mas in separation and 0°.56/ρ in position angle, where ρ is the separation in arcseconds. These are the first results acquired using an improved intensified CCD detector. The new detector, in concert with an intensity-filtering technique applied in software, has permitted a 1 mag increase in dynamic range, to 3.5 mag, for pairs separated by about 2". The instrumentation and calibration are briefly described, with an emphasis on the characteristics of the new detector. The software filter used to increase the dynamic range is also described.