2 Selection of program stars and observations

Stars observable from the Northern Hemisphere were selected from Taylor's 1996 list of candidate SMR dwarf and subgiant stars. Spectra were obtained with the Sandiford cassegrain echelle spectrograph (McCarthy et al. 1993) attached to the 2.1 m Struve telescope at McDonald Observatory during three runs: 1996 June, 1996 August and 1996 December. Exposure times were typically 5 min each, resulting in signal-to-noise (S/N) ratios per pixel averaging near 250. A spectrum of a Th-Ar lamp was obtained following each star spectrum, ensuring accurate wavelength calibration. The resolving power (measured on the Th-Ar emission line spectra) averages near $R = 45\,000$.