Precise radial velocities of late-type stars in the open clusters M11 and M67

The authors have obtained precise radial-velocity measurements of 39 stars and 170 stars in the fields of the open clusters M11 and M67, respectively; by selection, the vast majority of the stars observed are cluster members. All stars observed are of spectral type later than F5; the data set includes essentially all of the giants in both clusters and all main-sequence stars in M67 brighter than V = 12.8, plus an assortment of nonmembers and fainter members. Single-measurement precisions range from 0.3 to 0.8 km s⁻¹. Almost all stars have been observed repeatedly, with cluster members typically having 5 - 25 velocity measurements. Observations were obtained over a span of 16 yr, although not all stars were observed throughout that period. The time distribution of the observations is a combination of low-frequency coverage (<1 yr⁻¹) over the first 11 yr and higher-frequency coverage (>2 yr⁻¹) over the final 5 yr.