METALLICITIES AND VELOCITIES OF OLD OPEN CLUSTERS

We have obtained moderate-resolution CCD spectra for giants in six old open clusters in the direction of the galactic anticenter [NGC 188, 6 705 (M11), 6819, 6939, 6940, and IC 4756]. Using cross-correlation tec hniques, we determined radial velocities for stars in each cluster and used these values to compute a cluster mean accurate to approximately 10 km s-1. These means agree quite well with published values. We the n used between four and six spectroscopic indices to measure the metal licity of each star and produce a mean cluster metallicity. Following the Galactic metallicity gradient, more distant clusters are metal poo r compared with clusters closer to the solar neighborhood. We used our data, which are centered around the solar radius, to supplement publi shed results by Friel and Janes (1993, A&A, 267, 75), and used the com bined data set to better define the Galactic metallicity gradient. We found that DELTA[Fe/H]/DELTAR(gc) = -0.097+/-0.017 dex kpc-1 for R(gc) > 7 kpc. This result agrees quite well with that of Friel and Janes a nd with that of other authors. We discuss a possible correlation betwe en age and Mg enhancement which is indicated by the differences betwee n Fe and Mg line strength among cluster giants. We also briefly consid er metallicity dependences with age and height above the Galactic plan e.