THE EQUIVALENT-WIDTH CALIBRATION OF THE KPNO ECHELLE SPECTROGRAPH

Equivalent widths measured from spectrograms obtained with the echelle spectrograph at the Kitt Peak National Observatory are compared in detail with measurements obtained from conventional coude spectrographs. Equivalent width measurements of the bright standard star Arcturus are used to recalculate the composition of that star. The results of all tests performed indicate that equivalent width measurements from the echelle spectrographs are in reasonable agreement with those obtained from other instruments, and can be used reliably to derive element abundances in stars. The degradation of resolution by the image tube should be considered in comparing echelle spectrograms to spectrograms from other instruments with similar reciprocal dispersion; measurements of equivalent widths in crowded spectral regions may be uncertain due to blending.