Authors: H. Gruenwaldt, M. Hilchenbach, E. Marsch, P. Bochsler, and F. Ipavich
Reference: Submitted Solar Wind 9 Paper
Abstract:
The absolute full disk solar flux has been measured in two wavelength bands,
one band extending from 0.1 to 77 nm and one centered on the 30.4 nm HeII
resonance line with a bandwidth of +/- 4 nm. The flux in these bands has been
measured using two nominally identical SOHO type transmission grating
spectrometers, one of which is being flown on SOHO and another which was on a
sounding rocket launched from the White Sands Flight Facility in New Mexico on
June 26, 1996. The primary purpose of the sounding rocket flight was to
provide "ground truth" calibration of the SOHO CELIAS/SEM spectrometer. The
SOHO CELIAS/SEM spectrometer data provide the photoionization rate of He which
is flowing into our solar system from the interstellar medium and,
additionally, provide a stable absolute EUV flux monitor for cross calibration
of other SOHO EUV instruments. A nearly continuous record of the full disk
solar flux has been measured since first light was observed on December 16,
1995. SOHO CELIAS/SEM results obtained since first light until September 30,
1996 will be presented as well as the calibration update based on the June 26,
1996 sounding rocket underflight data.