Radial velocities and metallicities from infrared Ca II triplet
  spectroscopy of open clusters: Berkeley 26, Berkeley 70, NGC 1798, and NGC
  2266
  Context: Open clusters are ideal test particles for studying the formation
and evolution of the Galactic disk. However, the number of clusters with
information about their radial velocities and chemical compositions remains
largely insufficient. Aims: We attempt to increase the number of open clusters
with determinations of radial velocities and metallicities from spectroscopy.
Methods: We acquired medium-resolution spectra (R~8000) in the region of the
infrared Ca II triplet lines (~8500\AA) for several stars in four open clusters
with the long-slit spectrograph IDS at the 2.5m Isaac Newton Telescope, Roque
de los Muchachos Observatory, Spain. Radial velocities were obtained by
cross-correlating the observed spectra with those of two template stars. We
used the relationships available in the literature between the strength of
infrared Ca II lines and metallicities to derive the metal content of each
cluster. Results: We provide the first spectroscopic determinations of radial
velocities and metallicities for the open clusters Berkeley 26, Berkeley 70,
NGC 1798, and NGC 2266. We obtain <V_r>=68$\pm$12, -15$\pm$7, 2$\pm$10, and
-16$\pm$15 km s$^{-1}$ for Berkeley 26, Berkeley 70, NGC 1798, and NGC 2266,
respectively. For Berkeley 26 we derive a metallicity of [Fe/H]=-0.35$\pm$0.17
dex. Berkeley 70 has a solar metallicity of [Fe/H]=-0.01$\pm$0.14 dex, while
NGC 1798 has a slightly lower metal content of [Fe/H]=-0.12$\pm$0.07 dex.
Finally, we derive a metallicity of [Fe/H]=-0.38$\pm$0.06 dex for NGC 2266.
