Comparison of the deep PEPSI spectrum of Arcturus with the KPNO Arcturus atlas from Hinkle et al. (2000). Panel a: numerous CH lines centered around the Fe I/Ca I blend at 4308 Å that constitute the Fraunhofer G-band. The dots are the PEPSI spectrum and the line is the KPNO atlas. The match is nearly perfect. Panel b: three wavelength regions where chromospheric activity may be detected. Each panel shows the ratio spectrum PEPSI:KPNO (line around unity), the KPNO spectrum as a line, and the PEPSI spectrum as dots. From left to right, the core of the Ca II H line, Hα , and the Li I 6707.9-Å line region.