Optical layouts of the WSO-UV spectrographs

Electron acoustic blow up solitary waves and periodic waves are studied in a classical unmagnetized plasma containing cold electron fluid, kappa distributed hot electrons and stationary ions. We obtain Korteweg-de Vries (KdV) equation for electron acoustic waves (EAWs) using the reductive perturbation technique (RPT). Applying bifurcation theory of planar dynamical systems to the obtained KdV equation, we prove the existence of electron acoustic blowup solitary and periodic wave solutions. Depending on different physical parameters, two types of exact explicit solutions of the mentioned waves are derived. Our model may be applied to explain blow up solitary and periodic wave features that may occur in the planetary magnetosphere and the plasma sheet boundary layer.     

UV detectors for spectrographs of WSO-UV project

The WUVS (WSO-UV Ultra Violet Spectrographs) consists of two high resolution spectrographs (R=50000) covering the Far-UV range of 115–176 nm and the Near-UV range of 174–310 nm, and a long-slit spectrograph (R=1000) covering the wavelength range of 115–305 nm. Significant progress in the CCD development gives a possibility to use back-illuminated CCD detectors with anti-reflection coating for observations in the UV. These detectors are under construction by e2v company (UK) based on their heritage of detectors production for numerous space missions including those for UV- and far-UV. The main parameters of WUVS detector subsystems are described.     

Gravitationally lensed QSOs in the ISSIS/WSO-UV era

Gravitationally lensed QSOs (GLQs) at 1≤z≤2 play a key role in understanding the cosmic evolution of the innermost parts of active galaxies (black holes, accretion disks, coronas and internal jets), as well as the structure of galaxies at intermediate redshifts. With respect to studies of normal QSOs, GLQ programmes have several advantages. For example, a monitoring of GLQs may lead to unambiguous detections of intrinsic and extrinsic variations. Both kinds of variations can be used to discuss central engines in distant QSOs, and mass distributions and compositions of lensing galaxies. In this context, UV data are of particular interest, since they correspond to emissions from the immediate surroundings of the supermassive black hole. We describe some observation strategies to analyse optically bright GLQs at z∼1.5, using ISSIS (CfS) on board World Space Observatory-Ultraviolet.     

Ultraviolet Astronomy: Astrophysical Perspectives of the Spektr-UF Project (WSO-UV)

Astrophysics - The prospects for astronomical observations in the ultraviolet (UV) are discussed in a brief review and the areas in which UV astronomy is especially in demand are listed. Some...     

WSO-UV project guide star catalogue: experimental verification of its photometric system

Precise pointing and stabilization of the T-170M telescope (World Space Observatory Ultraviolet, WSO-UV project) is provided by the Fine Guidance System (FGS) that uses a guide star catalogue (Master Catalogue). To verify the photometric system of the Master Catalogue we have carried out ground based observations with a CCD-camera in a spectral band, close to that of FGS. We have found, that the photometric quality of the Master Catalogue is sufficient for FGS operations. The mean photometric error in the range of 14–17 mag is ±0.23 mag; its variation over the sky does not exceed the factor of two. 2% of stars from the Master Catalogue have photometric errors higher than 2 mag. We have also found a correlation between large photometric errors and the Master Catalogue flags.     

Spectral studies of comets in the ultraviolet range and prospects of the WSO-UV project in these studies

Many problems of determining the chemical composition of comets and studying the physical processes in cometary nuclei can only be solved by using observational data in the UV range of the electromagnetic spectrum (115–300 nm). Cometary observations have a number of features in comparison with such studies of other astronomical objects. The World Space Observatory — Ultraviolet mission, planned for launch in 2021, will overcome most of the challenges in these studies and will be able to become an essential tool of cometary UV research in the following decade.     

Hopes and expectations with GREGOR

This contribution to the series of GREGOR inauguration articles addresses the history of the GREGOR telescope. It was obvious since a long time that the study of the atmospheric dynamics on the Sun needs telescopes with a large aperture. So the first plans to replace the 40 years old Gregory‐Coudé Telescope, with its 45 cm primary mirror, by a large, 1.5‐meter telescope date back to 1997. After a positive review of the project by the Deutsche Forschungsgemeinschaft in 2000, the large financial support started in 2000. Unfortunately, the new technology of the Cesic mirrors was not yet ripe to produce the large primary mirror with this light‐weight material. So, the project was much delayed. After recollecting for the reader several dates, I also go through some properties of GREGOR. I recall the aims of the project and discuss difficulties and ways to realise the intentions (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The imaging and slitless spectroscopy instrument for surveys (ISSIS) for the world space observatory-ultraviolet (WSO-UV)

ISSIS is the Imaging and Slitless Spectroscopy Instrument for the World Space Observatory-Ultraviolet (WSO-UV) mission. ISSIS is a multipurpose instrument designed to carry out high resolution (<0.1 arcsec) imaging in the far UV with fields of view ≥2×2 arcmin². ISSIS has two acquisition channels: the High Sensitivity Channel (HSC) and the Channel for Surveys (CfS). The HSC is equipped with an MCP-type detector to guarantee high sensitivity in the 1150–1750 ? range and high rejection of lower energy radiation. The CfS is equipped with a large CCD detector (4k×4k) to obtain images from the far UV to the red (1150–8500 ?); the CfS is implemented to allow observing UV bright sources such as reflection nebulae or nearby massive star forming regions. The design drivers and the current status of the instrument are described in this contribution.     

Crowded-field image simulator for WSO-UV/ISSIS: first functional version developed by the Glendama team

We are developing a web-based interactive software to simulate crowded-field imaging with ISSIS on board the future WSO-UV. This new tool is aimed to prepare WSO-UV/ISSIS proposals to observe multicomponent targets and dense fields. For a given combination of UV channel, filters and exposure time, the user creates a set of point-like and extended sources (source model). This source model produces a final image, which takes into account a pixelated field of view, a realistic conversion between physical flux and counts per second, the convolution with the expected point spread function, a sky background and noise fluctuations. The current version of the simulator is available at the Glendama website, and it allows users to specify all relevant parameters of each point-like or extended source, drag-and-drop sources by using a mouse or a fingertip/stylus on a touchscreen, change the frame size or the brightness scale, etc.     

Comet C/2010X1 (Elenin). Unrealized expectations

We present the analysis of the photometric and spectroscopic data obtained for comet C/2010 X1 (Elenin) when it was at a distance of 2.92 AU from the Sun. The observations were made at the prime focus of the 6-m BTA telescope with the SCORPIO focal reducer. The magnitude of the comet, measured in the R _c -band with an 9?? aperture radius amounted to 16?8 ± 0?1. The computed dust production rate was estimated to be about 6 kg/s. The cometary coma manifested the emissions in the (0?C0) band of the CN molecule violet system, and a number of emission band heads of the C₃ molecule. The gas production rate of the molecules is determined using the Haser model and amounts to 1.41 × 10²⁴ and 4.20 × 10²³ molecules per second for CN and C₃, respectively. The ratio of gas production rates log[Q(C₃)/Q(CN)] is equal to ?0.85, which is close to the mean value, determined for a significant number of comets. A normalized gradient of the cometary dust reflectivity, calculated for the 4430?C6840 ? spectral range amounts to 14.3 ± 1.2%.     

Weak lensing by galaxies in groups and clusters – I. Theoretical expectations

Three of the six southern Clube Areas that were mainly observed at the European Southern Observatory and whose principal results are given in Paper XVI are marginally observable from Haute-Provence. Additional measurements obtained on several observing runs there enabled orbits to be determined (in most cases rather poorly, owing to the paucity of data) for 30 of the newly discovered spectroscopic-binary systems; they are presented in this paper. One object, HD 33978, seems to be of such significance that special efforts have been made, largely by Drs J. Andersen and H. Lindgren, to obtain additional radial-velocity measurements. That system is shown to be a double-lined binary with a period of only 10.67 d despite one of its components being a late-type giant. The giant star has a projected rotational velocity of almost 40 km s⁻¹; it could be expected to exhibit RS CVn-type photometric variations, which have not yet been observed, in addition to the 'ellipsoidal variation', discovered by Hipparcos , which occasioned its designation as VV Lep.     

Venus O+ pickup ions: Collected PVO results and expectations for Venus Express

Observations of oxygen pickup ions by the plasma analyzer on the Pioneer Venus Orbiter (PVO) Mission arguably launched broad interest in solar wind erosion of unmagnetized planet atmospheres, and its potential evolutionary effects. Oxygen pickup ions may play key roles in the removal of the oxygen excess left behind from the photodissociation of water vapor by enabling direct escape, additional sputtering of oxygen when they impact the exobase, and escape as energetic neutrals produced in charge exchange reactions with the ambient exospheric oxygen and hydrogen. Although the PVO observations were compromised by an ∼8 keV energy limit for O⁺ detection, a lack of ion composition capability, and the limited sampling and data rate of the plasma analyzer which was designed for solar wind monitoring, these measurements provide our best information about the extended O⁺ exosphere and wake at Venus. Here we show the full picture of the spatial distribution and energies of the O⁺ ion observations collected by the plasma analyzer during PVO's ∼5000 orbit tour. A model of O⁺ test particles launched in the circum-Venus fields described by an MHD simulation of the solar wind interaction is used to help interpret the PVO observations and to anticipate the expanded view of Venus O⁺ escape that will be provided by the ASPERA-4 experiment on Venus Express.     

In-situ particle acceleration in extragalactic radio hot spots: observations meet expectations

We discuss, in terms of particle acceleration, the results from optical VLT observations of hot spots associated with radio galaxies. On the basis of observational and theoretical grounds, the following is shown. (i) Relatively low radio-radio power hot spots are the optimum candidates for being detected at optical waves. This is supported by an unprecedented optical detection rate of 70 per cent out of a sample of low radio power hot spots. (ii) The shape of the synchrotron spectrum of hot spots is mainly determined by the strength of the magnetic field in the region. In particular, the break frequency, related to the age of the oldest electrons in the hot spots, is found to increase with decreasing synchrotron power and magnetic field strength. Both observational results are in agreement with an in-situ particle acceleration scenario.     

Recent progress in CP star detection and classification

Chemically peculiar (CP) stars are mainly found among B and A stars. Present theories are not able to account fully for the observed spectrum anomalies, suggesting that in the atmospheres of stars in the range ofT _e , where mass loss is no longer very large and convection is still not very important, the present theoretical approach needs further refinement. Moreover, the lack of laboratory data is responsible, at least partly, for the discrepancies between observed and computed stellar energy distributions.The choice for quick detection of CP stars among faint objects is reviewed; the measure of the flux depression at 5200 appears to be very powerful, and the identification of this complex feature is urgently needed.The need to separate the various subclasses of the He abnormal stars in a standard way is underlined and further analyses of the characteristics of the Boo stars are required.The problem of the determination ofT _e and consequently of realistic atmospheric abundance anomalies of CP stars is discussed.     

Recent progress in imaging polarimetry

Recent instrumental developments in imaging polarimetry allow array detectors to reach a polarimetric sensitivity of 1 × 10^–4 of the intensity. New instrumental effects appear at these levels of sensitivity and generate spurious polarization signals with amplitudes of up to 5 × 10^–4. Here I discuss these effects and present methods to avoid them. Polarized spectra with an rms noise of 6 × 10^–6 may then be obtained. Furthermore a method is brought to the reader's attention that allows polarization measurements at the 1 × 10^–4 level with regular array detectors, e.g. in the near-infrared.     

Recent progress in the theory and application of symplectic integrators

In this paper various aspect of symplectic integrators are reviewed. Symplectic integrators are numerical integration methods for Hamiltonian systems which are designed to conserve the symplectic structure exactly as the original flow. There are explicit symplectic schemes for systems of the formH=T(p)+V(q), and implicit schemes for general Hamiltonian systems. As a general property, symplectic integrators conserve the energy quite well and therefore an artificial damping (excitation) caused by the accumulation of the local truncation error cannot occur. Symplectic integrators have been applied to the Kepler problem, the motion of minor bodies in the solar system and the long-term evolution of outer planets.     

Recent progress on anomalous X-ray pulsars

I review recent observational progress on Anomalous X-ray Pulsars, with an emphasis on timing, variability, and spectra. Highlighted results include the recent timing and flux stabilization of the notoriously unstable AXP 1E 1048.1–5937, the remarkable glitches seen in two AXPs, and the newly recognized variety of AXP variability types, including outbursts, bursts, flares, and pulse profile changes. I also discuss recent discoveries regarding AXP spectra, including their surprising hard X-ray and far-infrared emission, as well as the pulsed radio emission seen in one source. Much has been learned about these enigmatic objects over the past few years, with the pace of discoveries remaining steady. However additional work on both observational and theoretical fronts is needed before we have a comprehensive understanding of AXPs and their place in the zoo of manifestations of young neutron stars.      

Continued progress in electrophonic fireball investigations

The mechanism proposed in 1980 by Keay to explain the occasional observation of instantaneous electrophonic sounds from large meteor fireballs continues to gain support. This mechanism accounts for many of the empirical features of the phenomenon, and the detection of ELF electromagnetic waves by direct transduction explains various other geophysical electrophonic phenomena including early sounds from seismic events. The extension of Ceplecha's fireball model to include Revelle's criterion for turbulence leads to realistic estimates for the frequency of occurrence of electrophonic fireballs. It also appears possible that the type of electrophonic sound observed relates to the composition of the fireball.Geophysical electrophonic phenomena may explain many baffling reports from ancient historical writings.     

Airglow on Mars: Some model expectations for the OH Meinel bands and the O2 IR atmospheric band

This work presents model calculations of the diurnal airglow emissions from the OH Meinel bands and the O₂ IR atmospheric band in the neutral atmosphere of Mars. A time-dependent photochemical model of the lower atmosphere below 80 km has been developed for this purpose. Special emphasis is placed on the nightglow emissions because of their potential to characterize the atomic oxygen profile in the 50-80 km region. Unlike on Earth, the OH Meinel emission rates are very sensitive to the details of the vibrational relaxation pathway. In the sudden death and collisional cascade limits, the maximum OH Meinel column intensities for emissions originating from a fixed upper vibrational level are calculated to be about 300 R, for transitions v^′=9→v^′?8, and 15,000 R, for transitions v^′=1→v^′=0, respectively. During the daytime the 1.27 μm emission from O₂(), primarily formed from ozone photodissociation, is of the order of MegaRayleighs (MR). Due to the long radiative lifetime of O₂(), a luminescent remnant of the dayglow extends to the dark side for about two hours. At night, excited molecular oxygen is expected to be produced through the three body reaction O + O + CO₂. The column emission of this nighttime component of the airglow is estimated to amount to 25 kR. Both nightglow emissions, from the OH Meinel bands and the O₂ IR atmospheric band, overlap in the 50-80 km region. Photodissociation of CO₂ in the upper atmosphere and the subsequent transport of the atomic oxygen produced to the emitting layer are revealed as key factors in the nightglow emissions from these systems. The Mars 5 upper constraint for the product [H][O₃] is revised on the basis of more recent values for the emission probabilities and collisional deactivation coefficients.     

Recent progress on the Columbus Project and the Miror Laboratory program

This paper summarizes recent advances on the Columbus Project telescope and in the University of Arizona Mirror Lab. The Columbus telescope structure has been re-optimized to allow rapid changes between foci, while still maintaining high rigidity. Room has been made to translate secondary and tertiary spiders out of the light path to the center. A bill allowing construction of the telescope on Mt. Graham, Arizona, has been passed by Congress and signed into law. Two alternative enclosure designs, one with a co-rotating building and a second which opens like a flower, are being explored.A common baseline design for the 8 m honeycomb mirrors for both the Columbus and Magellan telescopes has been developed. It has stiffness comparable to that of the Palomar 200 inch mirror. The Mirror Lab has successfully cast two 3.5 m honeycomb blanks and expects to begin casting at the 6.5 and 8 m scale at the end of 1990. Interferometric tests of the Vatican f/1 1.8 m borosilicate honeycomb mirror show good stability of figure with the air jet ventilation system. A 60 cm stressed lap has been completed, and will be used to parabolize this mirror which is now polished as an f/1 sphere. Plans for a polishing facility to house two 8 m machines and a test tower are complete, with construction starting in April 1989.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.