SPECKLE INTERFEROMETRY AT THE US NAVAL OBSERVATORY. XX

Results are presented of 4222 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory in 2013 and 2014. These observations are averaged into 2335 mean relative positions and range in separation from 0 ''.53 to 83 ''.90, with a median separation of 11 ''.42. This is the 20th in this series of papers and covers the period 2013 January 4 through 2014 December 18. Also presented are 13 pairs which are measured for the first time, 12 pairs which appear to be lost, linear elements for 17 pairs, and orbital elements for five additional pairs. Finally, we investigated apparent systematic residuals to earlier measures in this series, and modify scale factors for closer pairs observed between 1990 and the present.