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Verified and updated calibrated absolute solar flux in the He II 30.4 nmspectral band-pass as measured by the Solar EUV Monitor (SEM) allows us tostudy variations of the solar EUV irradiance near the minima of Solar Cycles22/23 and 23/24. Based on eight (1996 to 2007) NASA sounding rocket flights, acomparison of SEM data with the measurements from three independent EUVinstruments was performed to verify and confirm the accuracy of the publishedSEM data. SEM calibrated data were analyzed to determine and compare minima forsolar cycles 22/23 and 23/24. The minima points were calculated using SEM firstorder daily averaged flux smoothed by a running mean (RM) filter with thewindow of averaging equal to 365 days. These minima occurred on June 2, 1996(22/23) and November 28, 2008 (23/24). The 23/24 minimum showed about 15% lowerEUV flux in the 30.4 nm band-pass than the 22/23 minimum. The 365-day RM curvearound the 23/24 minimum has significant asymmetry (fast decrease of the EUVflux to the minimum and a long, near-horizontal profile after the minimum).This profile is quite different from the much faster and symmetrical change ofthe flux around the 22/23 minimum. SEM flux was compared with both highspectral resolution (0.1 nm) Mg II index calculated from the Solar Radiationand Climate Experiment (SORCE) using the Solar Stellar Irradiance ComparisonExperiment (SOLSTICE) data and with the NOAA composite Mg II index spectrum.

Minima of Solar Cycles 22/23 and 23/24 as Seen in SOHO/CELIAS/SEM Absolute Solar EUV Flux