26 August 2009 EUVS-C: the measurement of the magnesium II index for GOES-R EXIS
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The EUV and X-ray Irradiance Sensors (EXIS) on the upcoming GOES-R mission will include a spectrograph to measure the Magnesium II doublet at 280 nm (channel C). The ratio of the core of this spectral feature to the line wings is the well-known Mg II index. This ratio is often used as a proxy for chromospheric activity, since changes in the index are highly correlated with changes in other chromospheric emission lines. As a ratio measurement, the Mg II index is relatively insensitive to instrumental effects. The A and B channels of the Extreme UltraViolet Sensor (EUVS) will make use of this fact and use the Mg II index measured by channel C in their degradation correction. EUVS C channel has sufficient spectral resolution and sampling to measure the Mg II index with high precision and will make this measurement at better than 30 s time cadence. This paper describes the design and measurement requirements of the C channel.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Martin Snow, Martin Snow, William E. McClintock, William E. McClintock, David Crotser, David Crotser, Francis G. Eparvier, Francis G. Eparvier, } "EUVS-C: the measurement of the magnesium II index for GOES-R EXIS", Proc. SPIE 7438, Solar Physics and Space Weather Instrumentation III, 743803 (26 August 2009); doi: 10.1117/12.828566; https://doi.org/10.1117/12.828566

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