Intensity cuts across the CH region at central meridian from Figure 1 on 22 September 2016, in units of digital numbers (DNs), ordered by temperature from top to bottom. An approximation of intensity contrast between the CH region and the surrounding quiet Sun, calculated using the Michelson contrast equation (1), is displayed in each graph. Difference in intensity between CHs and the surrounding corona is visually noticeable in the 171 Å (b), 193 Å (c), and 211 Å (d) passbands. CHs have a typical temperature of 0.7 MK, which means they should produce peak emission in the 171 Å passband.