Detection of solar 5 minute oscillations. Top panel: time series of 842 consecutive spectra around the Fe I 6280.57 Å line. Bottom panel: derived Doppler velocity of the Fe I line: the blue line shows the raw measured shift of the Fe line, the red line indicates the shift of the telluric O₂ line (used as a reference for spectrograph drift), and the black line represents the corrected Fe line shift after removal of the O₂ line drift, revealing oscillations with an amplitude of ∼±300 m s⁻¹.