• EUV;
  • solar minmum;
  • spectrum

[1] NASA sounding rocket 36.240 was launched from White Sands Missile Range in New Mexico on 14 April 2008. The primary instrument in this payload was the prototype extreme ultraviolet (EUV) Variability Experiment (EVE). The Multiple EUV Grating Spectrograph (MEGS) channels of EVE measure the solar irradiance from 6 to 106 nm at 0.1 nm spectral resolution. While the main purpose of this rocket flight is to provide the fifth underflight calibration for the Solar EUV Experiment (SEE), the importance of this rocket observation is the first observation of the solar EUV irradiance at high spectral resolution during solar cycle minimum conditions. The higher spectral resolution measurements will help resolve outstanding concerns about the previous solar soft X-ray irradiance results made with broadband photometers shortward of 27 nm, and the measurements provide the most accurate reference for the solar cycle minimum as part of the international Whole Heliosphere Interval (WHI) campaign.