Speckle Interferometry at the US Naval Observatory. XII

The results of 1657 speckle interferometric observations of double stars, made with the 26 inch (66 cm) refractor of the US Naval Observatory, are presented. Each speckle interferometric observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1111 mean relative positions and range in separation from 016 to 1699, with a median separation of 165. This is the 12th in a series of papers presenting measurements obtained with this system and covers the period 2005 January 3-December 29. Included in these data are 30 older measurements whose positions were previously deemed possibly aberrant but are no longer classified this way following a confirming observation. Sixteen of these systems have new orbital elements, which are presented here as well. For η Coronae Borealis (STF 1937) we determine masses of 1.207 and 1.077 M⊙ and an orbital parallax of 54.95 mas.