Complete RR Lyrae Las Campanas spectra

This directory contains spectra that have been used in multiple papers on RR Lyrae stars by George Preston and collaborators (e.g, ``The Axial Rotation and Variable Macroturbulence of RR Lyrae Stars'', 2019, AJ, 157, 153; G. W. Preston, C. Sneden, M. Chadid, I. B. Thompson, and S. A. Shectman), and in related investigations (e.g., ``On the Use of Field RR Lyrae as Galactic Probes. II. A new Delta-S calibration to estimate their metallicity'', 2021, ApJ, 908, 20; J. Crestani et al.). These spectra of RR Lyrae variables were obtained with the Las Campanas Observatory Du Pont Telescope and its echelle spectrograph. This instrument has a spectral resolving power R ~= 27,000. Integration times were almost always < 900 sec in order to avoid velocity phase smearing of the absorption features. Therefore the typical S/N values are < 30 in the individual spectra. Essentially all Du Pont spectra for this work collected in the years 2006-2014 on the RR Lyrae work led by George Preston are gathered here. The doubly-dimensioned echelle spectra are fully reduced and are on a laboratory wavelength scale. They are organized in subdirectories labeled by year and month of the observation. For example, subdirectory "files1005" contains the spectra obtained in May 2010. In a separate subdirectory "velocities" we have placed MS-EXCEL files that give the velocities of the target stars, along with the velocity uncertainties. Tabulated values of VREL, VOBS, and VHELIO are those defined in the VELOCITY COMPUTATION ALGORITHM section of the IRAF help page for fxcor.