Interferometric measurements have been made on 218 titanium lines in the region 3341–4186 Å with a Fabry-Perot étalon crossed with a Wadsworth spectrograph. Of the total number of lines photographed, 128 faint lines were measured along with 90 previously measured and revised standards.An internal consistency check for the 16 pairs of lines taken showed that the mean deviation from the weighted mean of two well-known multiplet separations was less than 0.002 Å, and that this deviation was consistent with the measurements of these lines.
JOHN F. GIULIANI and M. P. THEKAEKARA, "Interferometric Measurements of Faint Titanium Lines in the Region 3341–4186 Å," J. Opt. Soc. Am. 54, 460-460 (1964)