Absolute solar 30.4 nm flux from sounding rocket observations during the solar cycle 23 minimum

A transmission grating extreme ultraviolet (EUV) spectrometer, nominally id entical to the Charge, Element, and Isotope Analysis System/Solar EUV Monit or (CELIAS/SEM) instrument on the Solar and Heliospheric Observatory (SOHO) , has obtained accurate measurements of the integrated absolute solar extre me ultraviolet irradiance in an 8 nm band pass centered at 30.4 nm. The spe ctrometer also measured the EUV/soft X-ray flux, but those data will be rep orted in a later paper. The instrument was launched an two sounding rocket flights from White Sands Missile Range, New Mexico, on June 26, 1996, and a gain on August 11, 1997, to provide a SOHO underflight calibration database in the EUV. The full disk solar 30.4 +/- 40 nm fluxes measured by it on th e above 2 days were 1.21 x 10(10) and 1.42 x 10(10) photons cm(-2) s(-1) at 1 AU, respectively. These measurements have an absolute la uncertainty of 8.1%.