Solar flux and spectrum measurements in the EUV spectral region on board the KORONAS-I satellite

Abstract

Data on the equipment mounted on board the KORONAS-I satellite and solar flux measurements in the extreme ultraviolet range (λ<130 nm) are presented. A thermoluminescent technique was used for solar ultraviolet radiometry (SUR). Vacuum ultraviolet solar spectrometry (VUSS) equipment based on the gas-photoelectron spectrometry method was employed to measure the He II 30.4 nm line in the solar spectrum. The solar flux in the region λ <130 nm was 7.5 erg·cm−2s−1 and the Lyman alpha line intensity was (3.3–3.7) · 1011 quant·cm−2s−1 in the low solar activity period from March to June 1994. The intensity of the He II (30.4 nm) line was varied in the limits of (6.0–7.5)·109 quant·cm−2s−1 from the 4 th to the 7 th of March, 1994. No intensive solar flares were registered in the observation period. An increase in the solar flux by ∼15% was observed at λ <130 nm during the B4.5 X-ray flare (June 30, 1994, 01 h 08 m UT).