Temporal changes in the spectrum of KIC 11971405. The average of the two consecutive exposures from October 2010 is plotted on the top using a black solid line, while the average spectrum from June 2015 is shown below with a red solid line with an offset of −0.15 in flux units. For clarity, the average from 2010 is repeated in the background using a grey solid line. The sharp absorption features in the bottom panel are telluric lines.