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EisXstudy
EisXstudy

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At line 113 changed one line
EIS makes images of different widths every time it takes an exposure (and disperses it). Slit spectra contain direct spectroscopic information, but take time to build up information over areas (see ''Raster Type'' above). To make slit spectra, EIS uses two slits: 1" and 2" in width. The 1" slit has less spatial coverage (because it is narrower) so there is sharper spectral resolution; meanwhile, the advantage of the 2" slit is that it is twice as wide, and thus it can accumulate photons twice as quickly as the 1" slit. (Note that this argument does not extend linearly to the width of the slots).
EIS makes images of different widths every time it takes an exposure (and disperses it). Slit spectra contain direct spectroscopic information, but take time to build up information over areas (see ''Raster Type'' above). To make slit spectra, EIS uses two slits: 1" and 2" in width.
The 1" slit has less spatial coverage (because it is narrower) so there is sharper spectral resolution; meanwhile, the advantage of the 2" slit is that it is twice as wide, and thus it can accumulate photons twice as quickly as the 1" slit. (Note that this argument does not extend linearly to the width of the slots).
At line 115 changed one line
For more image-based information, at the expense of line profile information, we can make slot images (scanning or sit'n'stare). In both cases the images are dispersed on the detector. The slot images are a sort of convolution of a spectrum with an image. However, the narrow slot — 40" wide — has been chosen so that essentially monochromatic images of the Sun can be made in many lines, without significant blending with images made in nearby lines. The width of the wider slot — 266" — was chosen for ground calibration reasons. However, the Fe XV line at 284 Å is sufficiently removed from other active region lines that we can essentially make images of only Fe XV in bright coronal loops.
For more image-based information, at the expense of line profile information, we can make slot images (scanning or sit'n'stare). In both cases the images are dispersed on the detector. The slot images are a sort of convolution of a spectrum with an image. However, the narrow slot — 40" wide — has been chosen so that essentially monochromatic images of the Sun can be made in many lines, without significant blending with images made in nearby lines.
At line 119 added 2 lines
The width of the wider slot — 266" — was chosen for ground calibration reasons, rather than scientific considerations. However, the Fe XV line at 284 Å is sufficiently removed from other active region lines that we can essentially make images of only Fe XV in bright coronal loops. In other lines, the images resemble the ''overlappograms'' produced by the ''Skylab'' S020 spectrograph (see Figure 2 of [http://solar.physics.montana.edu/reiser/] for a full-Sun idea of what this means), though with smaller spatial extent.
This page (revision-57) was last changed on 07-Dec-2016 14:14 by David R WilliamsTop