M. J. Abbott

The Extreme Ultraviolet Explorer Stellar Spectral Atlas

We present an atlas of extreme ultraviolet (EUV) spectra of 95 bright stellar sources observed between 1992 July and 1996 June with the Extreme Ultraviolet Explorer (EUVE) spectrometers. These data are taken in the short- (SW; 70-190 A), medium- (MW; 140-380 A), and long-wavelength bandpasses (LW; 280-760 A) at roughly 0.5, 1, and 2 A resolution, respectively. We describe the spectrometers and detail the procedure used to reduce the observational data to spectra. The atlas is grouped by the type of source: O-A stars, F-M stars, white dwarfs, and cataclysmic variables. We present a brief overview of the general nature and EUV spectral distribution of each group and present accompanying notes and individual spectra for each source. We show selected F-M sources in more detail with identifications of the brightest spectral lines illustrating the characteristics of the EUV spectra of stars of various temperatures. The current study is the most complete compilation to date of aggregate spectra of bright EUV stellar sources.

In-orbit performance of the spectrometers of the Extreme Ultraviolet Explorer

The Extreme Ultraviolet Explorer (EUVE), launched on June 7, 1992, is an extremely successful NASA astrophysics mission that contains three extreme ultraviolet (EUV) spectrometers designed to be used in pointed spectroscopic observations of astrophysical sources in the 70-760 angstrom wavelength region. The spectrometers utilize a slitless design based on grazing- incidence optics and variable line-space gratings. Detailed wavelength scales determined from ground-based calibrations and refined with in-orbit data are used to assign wavelengths for each detected photon to within half a resolution element (less that 0.8 angstrom in all cases). Spectral resolving power (FWHM of non-Gaussian profiles) varies in the range R approximately 150-450. Spectrometer throughputs were determined from an extensive laboratory calibration and then were adjusted slightly based on in-flight calibration spectra of known astrophysical continuum sources (hot DA white dwarf stars). We also have measured count rates from the detector and the geocoronal and distributed backgrounds, parameters critical to assessment of accurate flux levels from the astrophysical sources.