Authors: D.L. Judge, D.R. McMullin, and H.S. Ogawa
Reference: Draft to be submitted to the Journal Geophysical Research, 1999
A transmission grating extreme ultraviolet spectrometer, nominally identical to the CELIAS/SEM instrument on SOHO, has obtained accurate measurements of the integrated absolute solar Extreme Ultraviolet (EUV) irradiance in an 8 nm bandpass centered at 30.4 nm. The spectrometer also measured the EUV/soft X- ray flux but those data will be reported in a later paper. The instrument was launched on two sounding rocket flights from White Sands Missile Range, NM on June 26, 1996 and again on August 11, 1997, to provide a SOHO underflight calibration data base in the EUV. The full disk solar 30.4 nm fluxes measured by it on the above two days were 1.21x10^10 and 1.42x10^10 photons cm-2 s-1 at 1 AU, respectively. These measurements have an absolute uncertainty of 8.1%.