Transmitted signals of the Ca I transitions at 6162.27 Å (top panel), 6439.1 Å (middle panel), and 6493.78 Å (bottom panel) using pass-bands of ×3, ×4.5, and ×6 the stellar line width derived from fitting a Voigt profile. The significance of measurements were derived from the in-out scenario in the bootstrap analysis described in Sect. 2.3.1. The noise levels were derived from the in-in and out-out scenarios of the bootstrap analysis.