Extreme Ultraviolet Explorer spectrometer.

The design and calculated performance is described for a spectrometer included on the Extreme Ultraviolet Explorer (EUVE) astronomical satellite. The instrument is novel in design, consisting of three plane reflection gratings mounted in the converging beam behind a grazing incidence telescope. This configuration is based on new varied line-space (VLS) gratings which have recently been proposed. A sample EUVE grating has been mechanically ruled and experimentally characterized. It recovered over 80% of the theoretical efficiency of perfectly formed grooves, reaching 38% absolute at a wavelength of 114 A. The grating was used to construct a laboratory spectrographic version of the EUVE spectrometer and recorded the spectrum of helium from 228 to 320 A. The spectral resolution was λ/Δλ ∼ 2000 and the image heights were ∼10 sec of arc. Individual spots were ∼25 × 50 μm, which is a significant improvement over existing grazing incidence spectrographs. A line profile measurement at 1 A away from first order 304 A showed <1.5%/ A of grating stray light and a rapid decline toward the wings. In visible light, no grating stray or ghost light could be seen. Three flight spectrometer channels in combination span the 70–760-A band with an effective collecting area of 0.3–1 cm2 over the 80–600-A region. The spectrometer has an inherent resolution of λ/Δλ ∼ 300, but if combined with a worst-case satellite performance will yield a spectral resolution of λ/Δλ = 110–240 and a spatial resolution of 1–2 min of arc. For a 40,000-sec observation, the average 3σ sensitivity to continuum flux is ∼2 × 10−27 erg/cm2/sec/Hz. This is a factor of 100 dimmer than a bright known EUV source and is comparable to the sensitivity of the all-sky survey which will be carried out on the EUVE. At a 5σ detection threshold, the spectrometer sensitivity to individual spectral lines is 1–4 × 10−3 photons/cm2/sec, which is a factor of 50 better than available with the EUVE wide bandpass telescopes. Simulated observations of two known classes of extrasolar EUV sources reveal rich spectra. During a six-month spectroscopic phase, target selection will be conducted by guest investigators chosen by NASA.

[1]  H. Wolter.  Spiegelsysteme streifenden Einfalls als abbildende Optiken für Röntgenstrahlen , 1952 .

[2]  Christopher D. Martin,et al.  WEDGE-AND-STRIP ANODES FOR CENTROID-FINDING POSITION-SENSITIVE PHOTON AND PARTICLE DETECTORS. , 1981 .

[3]  Oswald H. W. Siegmund,et al.  Detection of Extreme UV and Soft X-Rays with Microchannel Plates: A Review , 1983 .

[4]  J. Underwood,et al.  Grazing incidence relay optics. , 1982, Applied optics.

[5]  Peter Predehl,et al.  Fabrication Of Transmission Gratings For Use In X-Ray Astronomy , 1982 .

[6]  S. Bowyer,et al.  Variable line-space gratings: new designs for use in grazing incidence spectrometers. , 1983, Applied optics.

[7]  S. Bowyer,et al.  Spectroscopy of the EUV (350–1400 Å) nightglow , 1984 .

[8]  James Liebert,et al.  White Dwarf Stars , 1980 .

[9]  R F Malina,et al.  Continuous discharge Penning source with emission lines between 50 A and 300 A. , 1979, Applied optics.

[10]  L. W. Acton,et al.  Large-aperture high-resolution x-ray collimator for the Solar Maximum Mission. , 1980, Applied optics.

[11]  S. Bowyer,et al.  Continuous-readout extreme-ultraviolet airglow spectrometer. , 1981, Applied optics.

[12]  S. Engman,et al.  Blaze characteristics of echelle gratings. , 1982, Applied optics.

[13]  J. Blamont,et al.  Extreme Ultraviolet Observations from Voyager 2 Encounter with Jupiter , 1979, Science.

[14]  J. Blamont,et al.  Extreme Ultraviolet Observations from Voyager 1 Encounter with Jupiter , 1979, Science.

[15]  A. Dupree.  The astrophysical interest of EUV observations of extra-solar objects , 1981 .

[16]  F. Paresce,et al.  Continuous discharge line source for the extreme ultraviolet. , 1971, Applied optics.

[17]  Asher Peres,et al.  Gravitational radiation damping of nongravitational motion , 1960 .

[18]  H. Rowland.  XXXIX. Gratings in theory and practice , 1893 .

[19]  M. Lampton,et al.  The Extreme Ultraviolet Explorer , 1981, Other Conferences.

[20]  W. Hunter,et al.  Optical Properties of Evaporated Rhodium Films Deposited at Various Substrate Temperatures in the Vacuum Ultraviolet from 150 to 2000 Å , 1971 .

[21]  C Martin,et al.  Extreme UV measurements of a varied line-space Hitachi reflection grating: efficiency and scattering. , 1984, Applied optics.

[22]  R Tousey,et al.  Extreme ultraviolet spectrograph ATM experiment S082B. , 1977, Applied optics.

[23]  M. Bottema.  Echelle Efficiency And Blaze Characteristics , 1981, Optics & Photonics.

[24]  Stuart Bowyer,et al.  An intense extreme-ultraviolet source in Cetus. , 1976 .

[25]  M. Oda.  High-Resolution X-Ray Collimator with Broad Field of View for Astronomical Use , 1965 .

[26]  Stuart Bowyer,et al.  Discovery of a nonsolar extreme-ultraviolet source , 1976 .

[27]  Jay A. Bookbinder,et al.  The stellar contribution to the galactic soft X-ray background , 1981 .

[28]  Francesco Paresce,et al.  A search for interplanetary He II, 304‐A emission , 1981 .

[29]  T. Zehnpfennig.  Development of a Slitless Spectrograph for X-Ray Astronomy , 1969 .

[30]  Keith O. Mason,et al.  HEAO 1 observations of X-ray emission from flares on dMe stars , 1979 .

[31]  H. Bräuninger,et al.  Aberrations of a facet-type transmission grating for cosmic x-ray and XUV spectroscopy. , 1978, Applied optics.

[32]  W. Rense,et al.  Method of increasing the speed of a grazing-incidence spectrograph , 1959 .

[33]  T. J. Tanaka,et al.  Low-energy x-ray interaction coefficients: Photoabsorption, scattering, and reflection: E = 100–2000 eV Z = 1–94☆ , 1982 .

[34]  J. Y. Uejio,et al.  Low-energy x-ray response of photographic films. I: Mathematical models , 1984 .

[35]  R. Green,et al.  The luminosity function of hot white dwarfs , 1980 .

[36]  R. Timsit,et al.  Erratum: A gas circulation system, using a Toepler pump, for the construction of a polarized 3He target [Rev. Sci. Instrum. 44, 1722 (1973)] , 1976 .

[37]  P. Sanford,et al.  An X-ray outburst from the RS CVn binary HR1099 , 1978, Nature.

[38]  A. Brinkman,et al.  Efficiency and resolution measurements of x-ray transmission gratings between 7.1 and 304 A. , 1980, Applied optics.

[39]  M. Bessell,et al.  The Space Density of Hot White Dwarfs , 1983, Publications of the Astronomical Society of Australia.

[40]  D. York,et al.  Synthesis maps of ultraviolet observations of neutral interstellar gas , 1983 .

[41]  William Ralph Hunter,et al.  Optical properties of evaporated platinum films in the vacuum ultraviolet from 220 Å to 150 Å , 1979 .

[42]  E. M. Reeves,et al.  The extreme-ultraviolet spectrum of a solar active region. , 1973 .

[43]  T. Harada,et al.  Mechanically ruled aberration-corrected concave gratings. , 1980, Applied optics.

[44]  C Martin,et al.  Quantum efficiency of opaque Csl photocathodes with channel electron multiplier arrays in the extreme and far ultraviolet. , 1982, Applied optics.

[45]  Richard C. Puetter,et al.  Collimators for soft X-ray measurements , 1976 .

[46]  C. Lindsey.  Effects of diffraction in multiple-grid telescopes for X-ray astronomy , 1978 .

[47]  D. S. Hall,et al.  Coordinated ultraviolet, optical, and radio observations of HR 1099 and UX Arietis , 1978 .

[48]  William Ralph Hunter,et al.  On the use of classical and conical diffraction mountings for XUV gratings , 1978 .

[49]  M. Lampton,et al.  Extreme-ultraviolet observations of a flare on Proxima Centauri and implications concerning flare-star scaling theory , 1977 .

[50]  Henry A. Rowland,et al.  Preliminary Notice of the Results Accomplished in the Manufacture and Theory of Gratings for Optical Purposes , 1882, Nature.

[51]  W. Hunter,et al.  The optical properties of evaporated gold in the vacuum ultraviolet from 300 Å to 2 000 Å , 1964 .

[52]  S. O. Kastner,et al.  Aspheric grating for extreme ultraviolet astronomy. , 1978, Applied optics.

[53]  J. H. Underwood,et al.  The GSFC EUV and X-ray spectroheliograph on OSO-7 , 1974 .

[54]  D. Maystre,et al.  Le theoreme de reciprocite pour les reseaux de conductivite finie: Demonstration et applications , 1974 .

[55]  M C Hettrick.  Aberrations of varied line-space grazing incidence gratings in converging light beams. , 1984, Applied optics.

[56]  R. L. Hilliard,et al.  Echelle efficiencies: theory and experiment. , 1980, Applied optics.

[57]  W G Fastie,et al.  Comprehensive analysis of gratings for ultraviolet space instrumentation. , 1978, Applied optics.

[58]  E. Loewen,et al.  Simple selection rules for VUV and XUV diffraction gratings. , 1978, Applied optics.

[59]  W. Cash,et al.  X-rays from RS Canum Venaticorum systems - A HEAO 1 survey and the development of a coronal model , 1980 .

[60]  L. Malinovský,et al.  An Analysis of the Solar Extreme-Ultraviolet Between 50 and 300 A , 1973 .

[61]  Y. Kondo,et al.  Uv spectra of nearby white dwarfs and the nature of the local interstellar medium , 1982 .

[62]  R. Hatcher,et al.  Theory of the Echelette Grating. III , 1958 .

[63]  P. Szkody,et al.  Extreme-ultraviolet observations of dwarf novae from Apollo-Soyuz , 1978 .

[64]  S. Bowyer,et al.  Extreme-ultraviolet spectrophotometry of the hot DA white dwarf HZ 43: detection of He II in the stellar atmosphere , 1982 .

[65]  John Heise,et al.  Calibration and efficiency of the Einstein objective grating spectrometer. , 1982, Applied optics.

[66]  S. Bowyer,et al.  Evidence for an interstellar or interplanetary source of diffuse He I 584 A radiation. , 1973 .

[67]  H. Gursky,et al.  An image-forming slitless spectrometer for soft X-ray astronomy. , 1966, Applied optics.

[68]  Daniel Maystre,et al.  Experimental Verifications and Applications of the Theory , 1980 .

[69]  B. L. Henke,et al.  Techniques of Low Energy X-Ray Spectroscopy (0.1 to 2 keV Region) , 1974 .

[70]  S. Bowyer,et al.  Discovery of quiescent X-ray emission from HR1099 and RS CVn , 1978, Nature.

[71]  A. Broadfoot,et al.  Extreme-UV and far-UV observations of the white dwarf HZ 43 from Voyager 2 , 1980 .

[72]  J. Flamand,et al.  EXOSAT x-ray imaging optics. , 1981, Applied optics.

[73]  Michael Lampton,et al.  The microchannel image intensifier , 1981 .

[74]  F. R. Harnden,et al.  Results from an extensive Einstein stellar survey. , 1981 .

[75]  R. Petit,et al.  Some recent theorical results for gratings; Application to their use in the very far ultraviolet region , 1976 .

[76]  R. Stern,et al.  Mass absorption coefficients of Parylene N at soft x-ray and vacuum-ultraviolet wavelengths , 1975 .

[77]  D. Werthimer,et al.  Microchannel Plate EUV Detectors for the Extreme Ultraviolet Explorer , 1984, IEEE Transactions on Nuclear Science.

[78]  S. Bowyer,et al.  On the opacity of the interstellar medium to ultrasoft X-rays and extreme-ultraviolet radiation. , 1974 .