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Soft X-ray surveys proved the existence of a local hot bubble surrounding the solar system (Mc Cammon et al 1983). Recently two experiments measured the spectrum of this hot interstellar medium with solid state detectors during rocket flights between 300 and 1000 eV (Rocchia et al 1984). The good resolution of the experiment permitted to measure CV, CVI and OVII line emissivities with good accuracy. We use these data to put some constraints on a model where the emission comes from a supernova remnant expanding in a finite pressure medium (Cox and Anderson 1982). We show the importance of non equilibrium ionization phenomena.

X-80 is one of the five missions being studied by ESA and a candidate for selection. The scientific aims and the main characteristics of the model payload will be discussed.

We present a high-resolution Bragg spectrometer designed for the observation of the soft X-ray cosmic diffuse background. The instrument concept is derived from the de Broglie geometry for the study of extended sources. It consists in a mosaic of spherical TlAP crystals associated with position sensitive detectors located on the focussing surface. The spectral resolution and its variation with the field of view is estimated by Monte-Carlo simulations for different X-ray energies chosen among the most intense lines emitted by an astrophysical plasma in the temperature range 1–4×106K. The estimated sensitivity and the simulations of actual space observations show that the instrument is capable to separate the strongest lines emitted by the most abundant ions (OVII,OVIII, FeXVII, NeIX, etc.) and to ‘map’ the whole sky during a six month mission.

In this paper, we present preliminary results of soft X-ray diffuse background observations. We observed two particular regions of the sky in the 0.3–1.5 keV range. The detection system consisted of three independent, 1 cm diameter, cooled solid state detectors. Nearly overlapping fields of view subtended a solid angle of approximately 1/4 sr. Except for the field of view, the whole set was similar to that described in Schnopper et al. (1982) (hereafter referred to as paper 1). This system was flown on board a three-axis stalibized rocket. The flight took place at White Sands Missile Range on 1981 May 4 at 0755 UT.

A silicon semiconductor detector near the top of the atmosphere is used to search for strongly interacting particles in our galactic halo. The data exclude, as the dominant component of the halo, such particles with masses between ∼ 2 GeV/ c 2 and 10 5 GeV/ c 2 . Comparisons are made with a previously reported subterranean search for weakly interacting halo particles.

The observation of X-rays is a relatively new branch of Astronomy. As every new field of science this astronomy had an extremely fast and fruitful development. After twenty years of X ray exploration it is time to summarize the results and to envisage the future. This is the aim of this expose. After a brief review of the birth conditions of X-ray astronomy, a description of the main space missions is done. The most important results are explained and help to define the fields to be covered by the future missions. This leads to the description of the instruments which will be flown on future spacecrafts planned for the next ten years.

A new high resolution γ-ray spectrometer for astrophysical measurements has been jointly developed at Saclay and Toulouse. The instrument consists of a large Ge(Li) crystal (140 cm 3 ) cooled to liquid nitrogen temperature and actively shielded by a sodium iodide crystal. Spectral resolution and effective area, are respectively 3.0 keV (fwhm) and 2.7 cm 2 at 1 MeV. Three flights were carried out in Brazil (Dec. 76, Feb. 77) with a stabilized gondola. The total background counting rate was about 1- counts/s in the 0.1–8 MeV energy range at float altitude (2.9 g cm −2 residual atmosphere, 12 GV rigidity cutoff). The sensitivity of the detector is about 10 −3 photons cm −2 s −1 over the above energy range for three hours of observation of a point source. Preliminary results are described.

Broad band spectroscopic observations in the range of very low energy X-rays have revealed the existence of a diffuse component. This component is related to the existence of a hot phase of the interstellar medium heated at temperatures on the order of 1 to a few 106 K. The detection of emission lines with improved resolution spectrometers has strengthened the thermal origin of the radiation. The purpose of CORONA is to: carry out a high resolution spectroscopic study to determine the physical conditions in the interstellar plasma responsible for the emission (temperature, ionisation state, abundances); make a mapping with a resolution of about one degree or less of some hot spots which are supposed to have a complicated structure; look for a possible component produced by a non-thermal process. The payload consists of: a set of wide field of view Bragg spectrometers (λ/Δλ ~ 30 to 400) adapted for the observation of extended regions (a few 10 square degrees). The instruments cover the ranges 0.12-0.28 KeV and 0.35-1 KeV; a concentrator with a scintillating proportional counter at its focus for moderate spectral resolution (λ/Δλ ~ 5) and good angular resolution observations (15 arc min). CORONA is proposed by six laboratories (see the authors' list above) to the European Space Agency as a passenger for one of its future mission.

The salient features of X-80, a European X-ray Astrophysics Mission, and a candidate for selection as the next satellite in the European Space Agency's scientific programme, is described.

A multiplexX-ray image analyser is described. It consists in a time-modulated coded aperture associated with a solid state detector. The system combines the high efficiency and good spectral resolution of solid state spectrometers with the spatial resolution of the coded aperture (∼200 μ). The device can be installed at the focus of a grazing incidence telescope to make images and spectra of faint astronomicalX-ray sources.

THIS communication presents the final results of an analysis of the X-ray emission from the Crab Nebula in the 15 to 150 keV energy range. We carried out two balloon flights (on September 15 and September 22, 1970) and have already presented preliminary results from the first flight1. We have now analysed both flights, in which a total of 70,000 photons from the Crab Nebula were detected (about 15,000 photons from the pulsar).

Previously reported enhanced soft X-ray emission from the North-Galactic Polar region supports the theory of a hot interstellar component. This paper reports the first detection of line emission from the hot interstellar component in the North-Galactic-Polar region. Measurements were made with solid state Si(Li) detectors aboard a spin-stabilized rocket launched from the White Sands Missile Range on March 22, 1980. Two features are clearly present in the low energy portion of the spectrum derived from the data. They correspond to emission lines from C V (300 eV) and C VI (360 eV), and from O VII (560 eV) and O VIII (650 eV). The detection of emission lines coming from these highly stripped ions is direct evidence for the thermal origin of the emission and confirms the presence of a hot (1-million K) component in the interstellar medium.

The detection of single events like the absorption of γ or X-rays and a or p particles with cooled thermal detectors is now well established and first resolutions obtained are promising. We have more thoroughly investigated the possibilities of the composite bolometer which offers the advantage of separating the absorbtion, thermal diffusion and thermometric functions. An optimal configuration is the diamond composite bolometer with a monolithic thermistor. Experimental results are presented on the simultaneous detection of different kinds of events (α's + γ -rays and β's + X-rays) at 1 K temperature. These results confirm the high linearity of this detector (better than 1.5 per cent from 20 KeV to 6 MeV) and its ability to accept rather high counting rates (> 100 per second). As a conclusion, we present an example of application to X-ray astronomy and we underline some problems or developments to be studied for a space mission.

This paper describes a multiplex image coding system designed to be associated with a non-imaging spectrometer (Si(Li) or thermal spectrometer). The resulting instrument, an imaging spectrometer, could be used as a focal instrument for an astronomical grazing incidence telescope. The coding system consists in a movable mask with pseudo randomly distributed holes, located in the telescope focal plane. The pixel size lies in the range 100-200 microns. The close association of the coder with a Si(Li) spectrometer or with an X-ray bolometer gives an imaging spectrometer combining the good efficiency ( >50% between 0.1 and 10 keV) and energy resolution ( ΔE~100 eV for Si(Li),~ 10 eV (expected) for a bolometer) of these energy dispersive devices, with the spatial resolution of the mask.

In this paper, we present preliminary results of soft X-ray diffuse background observations. We observed two particular regions of the sky in the 0.3–1.5 keV range. The detection system consisted of three independent, 1 cm diameter, cooled solid state detectors. Nearly overlapping fields of view subtended a solid angle of approximately 1/4 sr. Except for the field of view, the whole set was similar to that described in Schnopper et al. (1982) (hereafter referred to as paper 1). This system was flown on board a three-axis stalibized rocket. The flight took place at White Sands Missile Range on 1981 May 4 at 0755 UT.

The X-ray properties of the supernova remnant G 29.7 – 0.3 are discussed based on spectral data from the EXOSAT satellite. In the 2 to 10 keV range a featureless power-law spectrum is obtained, the best-fit parameters being: energy spectral index α -0.77, hydrogen column density on the line of sight NH= 2.3.1022 cm-2. The incident X-ray flux from the source is (3.6 ± 0.1) 10-11 erg cm-2 s-1 in the 2 to 10 keV range corresponding to an intrinsic luminosity of about 2.1036 erg s-1 for a distance of 19 kpc. The source was not seen with the imaging instrument thus constraining the hydrogen column density to be NH = (3.3 ± 0.3) 1022 cm-2 and the energy spectral index α = 1.0±0.15. This new observation is consistent with emission by a synchroton nebula presumably fed by an active pulsar. An upper limit of ~ 1.5% for the pulsed fraction in the range of periods 32ms to 104 s has been obtained.

THIS report presents the final results of observations of pulsations in the X-ray flux in the 2.5 to 30 keV range coming from the direction of the Crab Nebula.

We analysed ten Libyan Desert glasses (LDGs) for chemical composition by ICP-AES and ICP-MS and four samples for their Sr and Nd isotopic compositions. Our results confirm the close compositional relationship of LDGs to mature sandstones. The glasses are LREE enriched (La n /Sm n = 4.2–4.5), and display significant negative Eu anomalies (Eu/Eu∗ = 0.6–0.75) similar to post-Archaean sediments. In addition, most element abundances are correlated with REE contents. The correlations are interpreted as mixing lines and strongly suggest that the parent material was composed of quartz grains coated with a mixture of kaolinite, FeTi oxides, and accessory phases. Significant PGE concentrations were measured in the dark coloured part of an LDG sample. Its normalized-pattem is chondritic, demonstrating the presence of a meteoritic component in the glass. Several hypotheses have been proposed for the origin of LDGs. However, our results confirm that LDGs are impact-derived glasses and have some petrographical and chemical features similar to those of Muong Nong-type tektites. Neodymium and Sr isotopic signatures of LDGs are consistent with their derivation by melting of mature sandstones derived from Proterozoic materials such as the East Saharan basement rocks. The most likely target rocks are the quartz arenites of the Jurassic-Cretaceous Nubia Group.

Soft X-ray surveys proved the existence of a local hot bubble surrounding the solar system. Recently two experiments measured the spectrum of this hot interstellar medium with solid state detectors during rocket flights between 300 and 1000 eV [4-7]. The good resolution of the experiment permitted to detect C V, C VI and O VII lines. In this paper we intend to compare results obtained during these two flights and discuss temperature and abundance determinations from the X-ray spectroscopic measurements already available. In particular the Solid State Spectrometer results are compared with those obtained by a Japanese Group using a Gas Scintillation Proportional Counter [3].

The North Polar Spur (or Loop I) is a very large feature appearing in large scale radio maps. Soft X-ray emission from this object stands out in soft X-ray maps between 0.5 and 1 keV. The brightest region lies around 1II ~ 25°, bII ~ 25°. We discuss a soft X-ray observation of the Spur obtained with solid state detectors [1]. This spectrum is decomposed in emission lines and the uncertainty on each line is estimated. The derived abundances are compatible with normal galactic abundances, in contradiction with previously published results [2].

A proposal for a European X-ray astronomy satellite includes a lunar occultation technique for the more accurate observation of new and existing X-ray sources.

The medium-energy experiment on board Exosat was used to measure the X-ray spectrum of the Kepler supernova remnant over the range 1.5-10 keV. An Fe emission line was clearly resolved with an energy of about 6.5 keV and equivalent width of about 1.8 keV. This was superposed on a continuum with a temperature of 5.0(+3.8, -1.9) keV. The medium-energy spectrum is shown to be consistent with a model in which the Kepler SNR is presently in a Sedov phase of evolution, the 5 keV continuum arises from the shocked interstellar/circumstellar medium, and thermal (but not ionization) equilibrium exists between electrons and ions behind the primary shock front. However, in this case, an overabundance of iron by more than 6 times cosmic is required. 28 refs.

A soft X-ray, 0.3-1.0 keV spectrum from a 1 sr region which includes a portion of the North Polar Spur, obtained by three rocketborne lithium-drifted silicon detectors, shows the C V, C VI, O VII and O VIII emission lines. The spectrum is well fitted by a two-component, modified Kato (1976) model, where the coronal emission is in collisional equilibrium, with interstellar medium and North Polar Spur temperatures of 1.1 and 3.8 million K, respectively.

The effects of Compton interactions of X- and ..gamma..-ray spectra with low-energy electrons are examined. It is demonstrated that the interactions can explain spectral singularities around 25 keV and 1 MeV observed in the X- and ..gamma..-ray diffuse-background spectrum. These interactions very likely occur in the source of radiation. Then most of the X- and ..gamma..-ray diffuse background would be due to a large number of unresolved, dense, extragalactic objects which might be galactic nuclei or quasars. Observations of some extragalactic X-ray objects confirm the existence of such sources. (AIP)

The global distribution of galactic X-ray sources (GXRSs) listed in the fourth Uhuru catalog (number-intensity, longitude, and latitude distributions) is reasonably well reproduced in the framework of three basic assumptions: (i) the creation rate of GXRSs, N/sub X/, varies with position within the galactic disk as a function of the ambient gas density p/sub g/ according to the relation N/sub X/=kp/sub g//sup n/, where k and n are free parameters; (ii) the luminosity function of GXRSs can be parametrized by dN/dLproportionalL/sup -alpha/; and (iii) X-ray sources are runaway systems.The best fit of the number-intensity distribution as well as of the longitude distribution is obtained with the two parameters n=1.35 and ..cap alpha..=1.1.The scale height of GXRSs is predicted to vary versus galactocentric distance. The latitude distribution of GXRSs is well reproduced when their azimuthal migration is taken into account, provided the mean velocity normal to the galactic plane is of the order of 100 km s/sup -/1.