HRTS results from spacelab 2

The HRTS instrument flew on the Spacelab 2 mission from 29 July - 6 August 1985. HRTS consisted of a 30 cm Gregorian telescope, a slit spectrograph covering the 1190–1680 Å region with 0.05 Å spectral resolution, a broadband (90 Å FWHM) spectroheliograph tuned to 1550 Å, and an H-alpha filter system. The spectrograph slit was 920 arc sec, approximately 1 R₀, in length. Sub arc second spatial resolution along the slit is possible, but because of jitter in the Spacelab Instrument Pointing System (IPS) good exposures actually achieved 1–2 arc sec resolution. We describe the scientific results from HRTS.     

The Magellan project

Magellan is one of the future space projects being studied by the European Space Agency. The aim is to provide high resolution (λ/Δλ ≥ 2.5 × 10⁴) spectra in the far and extreme UV (between 500 and 1550 Å) of faint galactic and extragalactic objects (V ≤ 16^m). The instrument consists of a mechanical collimator, a concave holographic grating and a bidimensional photon-counting detector. A low resolution mode (λ/Δλ ≥ 10³) will provide spectra of objects as faint as 18^m.5. Magellan is planned as an observatory, operated in real time, and allowing interaction with the observer.     

Vertical distribution of NH3 in the upper Jovian atmosphere from IUE observations

The first unambiguous identification of ammonia in the upper atmosphere of Jupiter has been obtained from the observation of individual NH₃ bands in an IUE high resolution spectrum in the 2100–2400 Å spectral range. The variation with wavelength of the strengths of these NH₃ bands implies that the NH₃ abundance has to be strongly reduced by photolysis in the upper jovian atmosphere. Preliminary analysis by means of scattering models shows that the ammonia mixing ratio cannot be constant with altitude. The mixing ratio NH₃/H₂ ranges from 5 10^?8 to 5 10^?7 at the 250 mb pressure level, and decreases as P or P² toward higher altitudes.     

Search for ultraviolet shuttle glow

The Space Shuttle Columbia flown in January 1986 carried two ultraviolet experiments (UVX) designed to observe very weak diffuse emission from various astronomical sources at wavelengths below 3200 Å with moderate spectral resolution. Such observations are extremely sensitive to the presence of any shuttle induced ultraviolet glow, since the wavelength range, 1200–3200 Å, includes strong emission lines or bands of species such as O, NO, and OH which are predicted to radiate strongly by models of the shuttle glow. The UVX spectrometers are sensitive to emission features as faint as 0.1 Rayleighs. Emissions from O₂, O and NO are detected and shown to be consistent with an atmospheric origin.     

Ultraviolet observations of Jupiter from Earth-orbiting satellites

The International Ultraviolet Explorer (IUE) has provided both improved spectral resolution and some spatial resolution for UV observations of Jupiter. Previous satellite observations have produced albedo curves for Jupiter showing the influence of Rayleigh scattering, and of some absorber(s) shortward of 2500Å on the UV spectrum. Constraints on the abundance of several minor constituents of the Jovian atmosphere were derived from the OAO-2 data. The IUE low dispersion data has a resolution of 8Å, making it possible to detect individual molecular features. A series of C₂H₂ absorptions in the 1750Å region have been identified, and indications of NH₃ absorptions are present in the 1950Å region.     

A future Japanese program in far-ultraviolet astronomy and solar physics

A design study of an ultraviolet-telescope satellite (UVSAT) has been carried out by the Japanese astronomical community. The main purpose of this satellite mission would be to investigate (i) the distribution and nature of ultraviolet sources in star clusters, galaxies, and clusters of galaxies, (ii) the physical structures of galactic nebulae, and (iii) the dynamics of stellar and galactic activity. A 60 cm, f/4 Cassegrain telescope will be launched into a semi-circular orbit of ～500 km altitude and of ～30° inclination, by an ISAS/Japan M3S-III rocket. An intensified CCD camera and/or a concave-grating spectrograph will be operated for the wavelength range λ?1200 Å. Various possible auxiliary instruments and sub-telescopes are considered.     

Bacterial cellulose may provide the microbial-life biosignature in the rock records

Bacterial cellulose (BC) is a matrix for a biofilm formation, which is critical for survival and persistence of microbes in harsh environments. BC could play a significant role in the formation of microbial mats in pristine ecosystems on Earth. The prime objective of this study was to measure to what extent spectral and other characteristics of BC were changed under the performance of BC interaction with the earthly rock – anorthosite – via microorganisms. The spectral analyses (Fourier Transform Infrared FT-IR, spectroscopy, and atomic absorption spectroscopy) showed unprecedented accumulation of chemical elements in the BC-based biofilm. The absorption capacity of IR by BC was shielded a little by mineral crust formed by microorganisms on the BC-based biofilm surface, especially clearly seen in the range of 1200–900 cm⁻¹ in FT-IR spectra. Confocal scanning laser microscopy analysis revealed that elements bioleached from anorthosite created surface coats on the BC nanofibril web. At the same time, the vibrational spectra bands showed the presence of the characteristic region of anomeric carbons (960–730 cm⁻¹), wherein a band at 897 cm⁻¹ confirmed the presence of β-1, 4-linkages, which may serve as the cellulose fingerprint region. Results show that BC may be a biosignature for search signs of living organisms in rock records.     

GRASP — A gamma-ray astronomy mission dedicated to the fine spectroscopy and positioning of celestial gamma-ray sources

The GRASP Mission - Gamma Ray Astronomy with Spectroscopy and Positioning - will be the first high resolution spectral imager to operate in the gamma-ray region of the spectrum. The instrument covers the photon energy range from approximately 15 keV to more than 100 MeV. A combination of discrete germanium solid state devices and scintillation counters form a position sensitive gamma-ray detection matrix which is operated in conjunction with a coded aperture mask to create arc minute images of the gamma-ray sky with a spectral resolution of typically λ/Δλ ∼1000. The use of a coded mask with a ‘zoom’ facility will permit the combination of field of view and angular resolution to be adjusted to suit the scientific aims of each observation. The respective continuum and line sensitivities will be typically 10⁻⁸ph cm⁻² s⁻¹ keV⁻¹ and 3 10⁻⁶ cm⁻² s⁻¹ for point sources of gamma-rays with photon energies close to 1 MeV.     

Discovery of highly ionized line emission in the far ultraviolet

We report the discovery of highly ionized line emission from CIVλ1550Å, OIII] λ1663Å, and OVI/SiIV λ1400Å, observed by the Berkeley UVX experiment on Shuttle mission 61-C. The CIV and OIII] lines were detected in 4 out of 8 directions, and the OVI/SiIV in 2 directions. The CIV line intensity exhibits a definite anticorrelation with HI column density, and shows significant pole brightening (a factor of 5 at least). There is evidence that the gas is not isothermal. When compared to observed CIV absorption column densities, we derive intrinsic densities of .01–.05 cm⁻³, and pressure p/k=1000–8000 (T/10 sup 5 K) cm⁻³ K, assuming the gas has a scale height of 2 kpc. Much higher densities and pressures are indicated if the gas is local (100–200 pc), which would give pressures in violation of canonical limits. Finally, we show that photoionized models, which break down at high densities because of charge exchange with HI, are inconsistent with the observed densities.     

The ROSAT mission

A primary scientific objective of the ROSAT mission is to perform the first all-sky survey with an imaging X-ray telescope leading to an improvement in sensitivity by several orders of magnitude compared with previous surveys. A large number of new sources (? 10⁵) will be discovered and located with an accuracy of 1 arcmin or better. These will comprise almost all astronomical objects from nearby normal stars to distant quasistellar objects. After completion of the survey which will take half a year the instrument will be used for detailed observations of selected sources with respect to spatial structure, spectra and time variability. In this mode which will be open for guest observers ROSAT will provide substantial improvement over the imaging instruments of the Einstein observatory.The main ROSAT telescope consists of a fourfold nested mirror system with 83 cm aperture having three focal plane instruments. Two of them will be imaging proportional counters (0.1 – 2 keV) providing a field of view of 2°, an angular resolution of ≈ 30″ in the pointing mode and a spectral resolution ^ΔE/E ≈ 45% FWHM at 1 keV. The third focal instrument will be a high resolution imager (≈ 3″). The main ROSAT telescope will be complemented by a parallel looking Wide Field camera which extend the spectral coverage into the XUV band.     

Balloon-borne far-infrared spectrophotometry of the galactic center region

Far-infrared observations of the Galactic Center have been carried through with the MPE Im balloon-borne telescope “Golden Dragon”. The measurements are composed of photometric scanning (33–95 μm) of the inner 4′×4′ and low resolution spectroscopy (δ^ν = 10 cm^?1) of the center and of a position approximately 1.5′ to the north. A Mars spectrum has been obtained for calibration. The spatial resolution of the photometry map is increased using the Maximum Entropy Method and the resulting map is compared to other observations in the same and other spectral regions. A clear asymmetry in the ring-like structure around the center indicates the presence of noncircular motions. The shape of the spectra is fairly smooth with at least no prominent dust features. A simple modelling shows a drastic increase of column density within 2 pc from the center and a modest drop over the next 3 pc to the north.     

HRTS observations of spicular emission at transition region temperatures above the solar limb

Slit spectra and spectroheliograph observations were obtained during the fourth rocket flight of the High Resolution Telescope and Spectrograph (HRTS) on 7 March 1983. A curved slit 900 arc sec in length was placed at the solar limb on the western edge of the south polar coronal hole, giving both coronal hole and quiet region coverage. In addition, spectroheliograph images tuned to cover a passband around 1550 Å (primarily C IV at 10⁵ K) were taken over an 8 × 15 arc min field. Simultaneous Hα images were obtained at Sac Peak Observatory. The C IV spectroheliograms show general spiked emission above the limb, and also several small loo- or prominence-like events. Slit spectra along the tops of several of these structures show tilted features which could be interpreted as rotational velocities of approximately 50 km s^?1.     

Infrared spectrometry of Venus from “Venera-15” and “Venera-16”

Fourier spectrometers for the investigation of infrared spectra of Venus were installed on the recent Soviet orbiters “Venera-15” and “Venera-16”. Many spectra with reliable absolute calibration were obtained in the 280–1500 cm^?1 region with a spectral resolution of 5 cm^?1 (ground based processing) and about 7 cm^?1 (preoprocessed on board) and a spatial resolution of about 100 km at the Venusian cloud top level. Bands of CO₂, H₂O, H₂SO₄ and SO₂ are identified. The 15 μm-CO₂- fundamental band was used for retrieval of altitude dependent temperature profiles. There are significant differences in the cloud structure above 60 km for distinct regions of Venus, demonstrated by differences in the spectra.     

Nightglow studies with the world's largest optical telescope

By making use of 0.02-nm-resolution sky spectra from the HIRES echelle spectrograph at the W.M. Keck(I) observatory on Mauna Kea, HI, obtained during normal astronomical observations, we have shown that 650–870 nm emission from the vibrationally-excited levels of the O₂(b¹Σ⁺_g) state is a significant component of the terrestrial nightglow, with a total average intensity from levels v = 1–15 of approximately 150 R. The b¹Σ⁺_g state vibrational distribution is bimodal, with peaks at v = 3, 4 and v = 12, and a deep minimum at v = 8 containing only ∼5% of the v = 3 population. The b-X 0-0 band (the Franhofer A-band) is discernible via isotopic emission, with an intensity comparable to that of the strongest of the new b-X bands. There are indications that the vibrationally-excited b¹Σ⁺_g state emissions correlate temporally with the OH Meinel band emission, and satellite measurements appear to show that the relatively strong emission from the O₂(b-X) 4-3 band originates at an alitutde near 87 km, i.e. in the OH region.In an 8-minute observation on 20 Nov 1999, the Keck telescope was pointed at Venus, and the first high-resolution nightglow spectrum was recorded in the visible spectral region. The oxygen green line was revealed, with an intensity near 150 R, approximately the same as in the terrestrial atmosphere. The only previous observation, from the Venera 9/10 orbiters, did not detect this emission.     

Long duration hard X-ray transatlantic payload

This note describes the HXR80M large area hard X-Ray Astronomy experiment. The payload is scheduled for a flight on board of a transatlantic balloon to be launched the next July from the Milo Base (Sicily), in the framework of the CNR experimental transatlantic campaign.The detectors are two Multiwire Spectroscopic Proportional Chambers (MWSPC) having 2,700 cm² sensitive area each.The two detectors are filled with an extremely pure Xenon-Isobutane mixture (impurity less than 1ppm) at high pressure (3–6 Atm) in order to obtain good spectral resolution and high efficiency. The field of view of the MWSPC's is limited by an array of three collimators each, having respectively 8°×8° and 5°×5° FWHM.The on board data handling is performed by microprocessor controlled electronics. In particular a micro Multichannel Analyzer (μMCA) is employed to obtain the spectrum of the detected photons. The scientific and housekeeping data are send to ground through a 1.2 Kbit PCM HF Telemetry link.The scientific aim of the experiment is the survey of the sky belt around the 38th parallel and in particular the observation of faint galactic objects and galactic binary systems in the range 15–200 keV.     

The bright mass ejection on the disk on October 14, 1980

A bright mass ejection appearing as a spray on the disk, associated with a 3b flare has been observed. A gap with a length of 2.5 × 10⁴ km and a width of 2 × 10⁴ km occurred between the flare and spray was observed. The intensity of the gap is about 1.6 times more intense than the undisturbed region. The spectral properties of the radio bursts corresponding to the flare and the spray are different. In addition, the flare and the spray are also different in their hard X ray emissions.Observation has not shown any relation between teh spray and the filament that existed previously in the active region. Perhaps the flare and the spray are produced simultaneously by the same mechanism. An observational model of the flare and the spray is shown in figure 3.     

The oriented scintillation spectrometer experiment for the gamma-ray observatory

The Oriented Scintillation Spectrometer Experiment (OSSE) for the Gamma Ray Observatory is described. OSSE uses four identical NaI(T1)-CsI(Na) phoswich detectors to provide gamma-ray line and continuum detection capability in the 0.05–10 MeV energy range. Additional gamma-ray and neutron detection capability is achieved above 10 MeV. Each detector has a CsI annular shield and a tungsten alloy collimator which define a 5° × 11° (FWHM) field-of-view. The detectors have independent, single-axis orientation systems which permit offset pointing to provide source-background subtraction. The sensitivity for line gamma rays in the 0.05–10 MeV region will be 2–3 × 10^?5 photons/cm²-s for a 10⁶-second observation period. The several modes of data acquisition and the emphases for the planned observational program are discussed.     

Fabrication and flight performance of a large area balloon borne hard X-ray telescope

We describe the fabrication and flight performance of a balloon-borne large area hard X-ray (20–100 keV) telescope for spectral studies of discrete cosmic X-ray sources. The telescope consists of two multi-wire Xenon filled proportional counters of effective area 1200 cm² each, mounted on an orientable platform. It can be pre-programmed to track any celestial source with a pointing accuracy of 0.5 degrees. For one hour of observation the telescope has a 5 σ detection sensitivity of 10⁻⁵ ph cm⁻² s⁻¹. The laboratory test results and the performance in a series of balloon flights conducted in 1984–1986 period is discussed and the preliminary results obtained for some X-ray sources are presented.     

Measurement of stratospheric trace constituent distributions from balloon-borne far infrared observations

Far infrared limb thermal emission spectra obtained from balloon borne measurements made as a part of the Balloon Intercomparison Campaign (BIC) have been analyzed for retrieval of stratospheric trace constituent distributions. The measurements were made with a high resolution Michelson Interferometer and covered the 15–180 cm⁻¹ spectral range with an unapodized spectral resolution of 0.0033 cm⁻¹. The retrieved vertical profiles of O₃, H₂O, HDO, HCN, CO and isotopes of O₃ are presented. The results are compared with the BIC measurements for O₃ and H₂O made from the same balloon gondola and with other published data. A comparison of the simultaneously retrieved profiles for several gases with the published data shows good agreement and indicates the validity of the far infrared data, the retrieval techniques and the accuracy of the inferred profiles.     

多谱段全日面极紫外成像仪

在极紫外波段对太阳进行成像观测是研究太阳活动、日冕中等离子体物理特性的重要手段.传统极紫外成像仪或光谱仪无法同时实现高光谱分辨率和大视场的太阳成像.本文设计了一种新型太阳极紫外多谱段成像系统,采用无狭缝光栅分光方式实现了高光谱分辨率和空间分辨率的全日面成像,成像视场可达47',光谱分辨率每像素2×10^-3 nm,空间分辨率每像素1.4',全日面时间分辨率优于60s.通过分析谱线的全日面成像图和系统响应,表明成像仪能大范围的观测太阳活动形态演化,为太阳物理研究和空间天气预报提供更完整的观测数据.