only sensitive to flares $\gtrsim$C5 level. The times at which MEGS-A and MEGS-B were exposed to the Sun around the time of a given flare are illustrated by the horizontal blue and cyan lines, respectively, as shown in the top-left panel of Figure \[sff\_plot\].

*Hinode* {#ss:hinode}
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The *Hinode* spacecraft [@kosu07] was launched into a Sun-synchronous orbit on 22 September 2006 and comprises three instruments: EIS, SOT, and XRT. They were designed to study the interplay between the photosphere and the corona by working in unison. However, by January 2008 *Hinode* had lost the use of its X-band transmitter, resulting in a dramatic reduction in the amount of data being transmitted to the ground.

### The Extreme-ultraviolet Imaging Spectrometer {#sss:eis}

EIS is a two-channel, normal-incidence EUV spectrometer. Its two channels cover the wavelength ranges 170–210Å and 250–290Å, selected to cover coronal emission lines with formation temperatures ranging from 8000 K (He [ii]{}) to 16 MK (Fe [xxiv]{}). It has a mirror that is tiltable in the solar X-direction, and is used to build up rastered spectral images of portions of the Sun in up to 25 spectral ranges. Additionally, EIS has both narrow (1$''$ and 2$''$ wide) slits, and wider 