We identified 56 narrow unblended lines, and used their line wavelengths
to create a template spectrum consisting of deltafunctions convolved
with the instrumental broadening (5km/s Gaussian σ).
The minimal distance between lines selected for the template was kept
at 1.5 Angstrom, to avoid blends in the cross-correlation function.
For each phase bin the we computed the cross-correlation function
of the stellar spectrum and the template spectrum. This effectively
combines the information contained in 56 separate spectral lines into
one CCF profile.
The resulting CCF profiles have very good
S/N, and were used as if they were real line profiles in the mode
identification.
