DAOSPEC: An Automatic Code for Measuring Equivalent Widths in High-Resolution Stellar Spectra

DAOSPEC is a Fortran code for measuring equivalent widths of absorption lines in stellar spectra with minimal human involvement. It works with standard FITS-format files and it is designed for use with high-resolution (R > 15,000) and high signal-to-noise-ratio (S/N > 30) spectra that have been binned on a linear wavelength scale. First, we review the analysis procedures that are usually employed in the literature. Next, we discuss the principles underlying DAOSPEC and point out similarities and differences with respect to conventional measurement techniques. Then, experiments with artificial and real spectra are discussed to illustrate the capabilities and limitations of DAOSPEC, with special attention given to the issues of continuum placement, radial velocities, and the effects of strong lines and line crowding. Finally, quantitative comparisons with other codes and with results from the literature are also presented.

Based on data obtained from UVES@VLT, GIRAFFE@VLT, HARPS@VLT located in the ESO observatory of Cerro Paranal, Cile. Also based on data from FOCES@CAHA 2.2-m telescope in Calar Alto, Spain. Data from the VALD and GEISA online databases have been employed as well.