The results of 2490 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1462 mean relative positions and range in separation from 0.56" to 71.80", with a mean separation of 14.81". This is the 18th in this series of papers and covers the period 2011 January 3 through 2011 December 18. Also presented are four pairs which are resolved for the first time, thirteen other pairs which appear to be lost, and linear elements for four additional pairs.
The results of 4747 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 2667 mean relative positions and range in separation from 0.328" to 95.9", with a median separation of 8.673". Eight orbits are improved. This is the 22nd in this series of papers and covers the period 2016 January 4 through 2016 December 29.
The results of 3989 intensified CCD observations of double stars, made with the 26-inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1911 mean relative positions and range in separation from 0.289" to 128.638", with a median separation of 8.669". Four orbits are improved. This is the 23rd in this series of papers and covers the period 2017 January 4 through 2017 September 13.
The results of 3611 intensified CCD observations of double stars, made with the 26inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1857 mean relative positions and range in separation from 0.341" to 128.644", with a median separation of 6.533". Two systems have their orbits improved and one has its first determination. This is the 24th in this series of papers and covers the period 2018 May 24 through 2019 October 28.
Position angles and separations resulting from 2406 speckle interferometric observations of 547 binary stars are tabulated. This is the second in a series of papers presenting measures obtained using the 66 cm refractor at the US Naval Observatory in Washington, DC, with an intensified CCD detector. Program stars range in separation from 0.2'' to 3.8'', with {delta}m {<=} 2.5 mag and a limiting magnitude of V = 10.0. The observation epochs run from 1993 January through 1995 August. Random errors are estimated to be 14 mas in separation and (0.52 degrees)/{rho} in position angle, where {rho} is the separation in arcseconds.
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 17.0mas in separation and 0.56{deg}/{rho} in position angle, where {rho} 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 1mag increase in dynamic range, to 3.5mag, 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.
The results of 1314 speckle interferometric observations of 625 binary stars, ranging in separation from 0.2" to 5.2" with a limiting secondary magnitude of V=11, are tabulated. These observations were obtained using the 66cm refractor at the US Naval Observatory in Washington, DC, with an intensified CCD detector. This is the fourth in a series of papers presenting measures obtained with this equipment and covers the period 1997 January 1 through December 31. Random errors for all measures are estimated to be 18mas in separation and 0.57{deg}/{rho} in position angle, where {rho} is the separation in arcseconds.
The results of 3056 speckle interferometric observations of double stars, made with the 26 inch (66cm) refractor of the US Naval Observatory, are presented. Each speckle interferometric observation of a system represents a combination of over a thousand short-exposure images. These observations are averaged into 1675 mean relative positions and range in separation from 0.19" to 45.21", with a median separation of 2.99". This is the ninth in a series of papers presenting measures obtained with this system and covers the period 2002 January 1 through 2002 December 29. Included in these data are 28 older measures whose positions were previously deemed possibly aberrant but are no longer classified this way following a confirming observation. Nine of these systems have new orbital elements, which are presented here as well.
The results of 1544 speckle interferometric observations of 637 binary stars, ranging in separation from 0.25" to 5.25", are tabulated. These observations were obtained using the 66 cm refractor at the US Naval Observatory in Washington, DC, with an intensified CCD detector. This is the fifth in a series of papers presenting measures obtained with this system and covers the period 1998 January 1 through December 31. Random errors for all measures are estimated to be 17.6 mas in separation and 0.55{deg}/{rho} in position angle, where {rho} is the separation in arcseconds.
The results of 1068 speckle interferometric observations of double stars, made with the 26 inch (0.66 m) refractor of the US Naval Observatory, are presented. These observations are averaged into 841 means of 815 binary stars. The systems range in separation from 0.22" to 6.01" with a mean separation of 2.21" and have a limiting secondary magnitude of V=12.5. This is the sixth in a series of papers presenting measures obtained with this system, and it covers the period 1999 January 1 through 2000 January 9.
