Hinode/EIS is a two-channel, normal-incidence EUV spectrometer. Its two channels cover the ranges
170-210 Å and 250-290 Å, and are designed to observe solar coronal emission lines. The scientific purpose of EIS is to study the response of the corona to changes observed by Hinode's Solar Optical Telescope (SOT) with its vector magnetograph and to compare observations with the full Sun-imaging X-Ray Telescope (XRT), also on-board.
EIS has a mirror which is tiltable in the Solar X direction, and is used to build up rastered spectral
images of the Sun in up to 25 spectral ranges. Additionally, EIS has both narrow (one- and two- arcsecond wide) slits, and wider (40- and 266-arcsecond) imaging slots, all with 512 arcseconds in the cross-dispersion (Solar Y) direction. Under nominal conditions, the 40-arcsecond slot can be used to make simultaneous, separated, quasi-monochromatic images in up to twelve strong emission lines covering a temperature range from He II (log T 4.9) to Fe XXIV (log T 7.2). EIS should be able to make
slit images of active regions in 10 seconds, of quiet Sun in between 30 and 60 seconds, and of flares in approximately one second.
Without moving the coarse mirror pointing, EIS is able to cover a spatial range in Solar X of 360 arcseconds. If the coarse mirror movement is engaged, EIS can off-point (in Solar X) from the centre of XRT's and SOT's pointing by almost one solar radius (890").