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Laboratory for Atmospheric and Space Physics


About ESP

ESP is provided by the University of Southern California (USC). ESP provides calibrations for MEGS sensitivity changes and higher time cadence (0.25-second). The ESP is very similar to the SOHO SEM instrument.


The Euv SpectroPhotometer (ESP) has 9 Si photodiodes behind a transmission grating:

  • ESP#1: 34.0-38.1 nm bandpass (Si IX, Si X, Fe XII, Fe XVI, & Mg IX emissions)
  • ESP#2: 23.1-27.6 nm bandpass (He II 25.6 nm emission + blend with weaker lines)
  • ESP#3: dark photometer to measure particle background (e.g., SEP)
  • ESP#4, 5, 6, & 7: 0.1-5.9 nm bandpass, zeroth order light with Ti-C filter, quadrant diodes that gives solar position and also flare location for the larger flares
  • ESP#8: 17.2-20.6 nm bandpass (Fe IX, Fe X, Fe XI, & Fe XII emissions)
  • ESP#9: 28.0-31.6 nm bandpass (He II 30.4 nm emission + blend with weaker lines)


ESP Spectrum

The ESP bands are shown as the white bands in this solar EUV spectrum

ESP Optical Layout

This picture shows the optical layout for the ESP. The solar radiation enters in from the right, goes through an Al-C filter, slit, and transmission grating, and then different wavelengths are diffracted to different photodiodes.