Authors: Judge, D.L., D.R. McMullin, H.S. Ogawa, D. Hovestadt, M. Hilchenbach, E.
Moebius, L.R. Canfield, R. Watts, M. Khne, and P. Wurz
Reference: 17th International Workshop/SOLERS22 1996 Workshop, June 17-21, 1996
National Solar Observatory/Sacramento Peak, Sunspot, New Mexico, USA
Group 4&5: contributed
Abstract:
The first results obtained with the Solar EUV Monitor (SEM) aboard the Solar
and Heliospheric Observatory (SOHO) will be presented. The SEM has measured
absolute solar EUV irradiance since December 16, 1995. The instrumentation
consists of a simple, light weight (480 gm) transmission grating (5000 bars/
mm) spectrometer fitted with a free standing aluminum filter immediately
behind the SEM entrance aperture to reduce the heat load on the grating and to
limit the wavelength range to the aluminum transmission region. The dispersed
light is detected by three aluminum coated photodiodes strategically placed
200 mm behind the grating. The zero order detector primarily measures the
irradiance within the nominal aluminum wavelength band pass (170 - 800 A), and
first order 304 A detectors measure the irradiance within an 80 A band pass
centered about the 304 A solar He II emission. The zero order channel is also
sensitive to soft x-rays shortward of approximately 120 A, while the first
order channels are not. A comparison of the zero order data with the GOES7
x-ray data (1-8 A) will be presented.