2. The SERTS-89 spectrum
The Solar EUV Rocket Telescope and Spectrograph (SERTS) has been flown on several occasions, returning the highest quality imaged extreme ultra-violet (EUV) spectra yet obtained of the Sun. A spectrum of an active region obtained in the 1989 flight was published by Thomas & Neupert (1994) and we will henceforward refer to this flight as SERTS-89.
The SERTS-89 instrument covered the 235-450 Å wavelength region in first order and 170-225 Å in second order, with sensitivity greatest above 300 Å as witnessed by Fig. 2 of Thomas & Neupert. The spectral resolution of nearly 10,000 is the highest yet achieved for this wavelength region, with line positions measured to a precision of 5 mÅ or better in most cases.
The published spectrum represents an average over an area of around 7" 276" across a solar active region. Subsequent re-evaluation of the absolute calibration scale for SERTS-89 indicates that all intensities reported in the catalogue should be increased by a factor of 1.24. However, to simplify comparison and because we are interested here only in relative values, we will continue to use the original intensity scale in the present work.
© European Southern Observatory (ESO) 1998
Online publication: November 24, 1997