The star Arcturus is among the brightest infrared sources in the sky, which makes it possible to observe the star at very high spectral resolutions. The infrared spectrum of Arcturus serves as a standard for our understanding of red giants (Arcturus is a K0III star). A very comprehensive spectral atlas of Arcturus was published by Hinkle, Walllace, and Livingston (1995). The observed spectrum is available through VizieR. Here for convenience, I’ve converted the appendices of atomic and molecular lines into comma-separated text files and converted the line centroids into microns. Lines are at vacuum wavelengths.