Intensive development of the radar method of investigating meteors and connected phenomena in the Earth's atmosphere required studying interaction of radio waves with ionized meteor trails. Approximate solutions of the problem of radio reflection by ionized meteor trails have been obtained in a number of papers (Feinstein, 1950; Herlofson, 1951; Kaiser and Closs, 1952; Manning, 1953, 1963; Eshleman, 1955; Brysk, 1958, 1959).

A survey for the molecules C2H and HC3N in a variety of interstellar clouds has been completed. Both molecules are very widespread, in cold dark clouds as well as in hot clouds. C2H emission has been mapped in L1534. In cold clouds the fractional abundance X(C2H) is found to be 2-6×10−9. The ratio of abundances X(C2H)/X(HC3N) falls in the range 6-10, consistent with some gas-phase reaction schemes for these molecules.

One way to realize the Large radio Telescope with a collecting area approaching one square kilometer, continuously covering a frequency range between 200 MHz and 2 GHz, is to construct a passive spherical reflector array of about 30 individual unit telescopes, each ∼ 300 m diameter(Butcher 1995). Valleys amid the hills of southwest China would be ideal for such LT concept. We refer to this effort as the Kilometer-square Area Radio Synthesis Telescope project. Site surveying and Radio Interference monitoring looks promising. Engineering considerations are summarized.

This paper discusses the short-period terms of nutation which are included in the recent theories of nutation for a rigid Earth. We argue that these terms should be expressed as terrestrial perturbations, that is as polar motion, and describe how such a transformation can be accomplished in practice. Based on the available rigid-Earth amplitudes, we estimate this lunisolar effect in polar motion for an elastic Earth with liquid core, and compare it to the oceanic and atmospheric perturbations at similar frequencies.

The 22·2 Mc./s. crossed array of the Carnegie Institution of Washington has been in use since 20 July 1954. This antenna system consists of two linear arrays 2047 ft. in length, each composed of sixty-six half-wave folded dipoles. The amplitude gains of the two arrays are, in effect, multiplied together by a phase-switching system similar to that used in phase-switching interferometers (Ryle, 1952) [1]. The design differs somewhat from the arrangement first used by Mills (Mills and Little, 1953) [2] in that the arrays are arranged in the form of a slightly flattened X. The resulting pencil beam is slightly elliptical in cross-section, measuring 1°·6 by 2°·4 at half-power points, and is directed by inserting lengths of line into the feeder system of each array, phasing the dipoles such that the maximum response is at the desired zenith angle.

Our 2dF Fornax Cluster Spectroscopic Survey (FCSS) and follow-up work in the Virgo Cluster have shown that the cores of both galaxy clusters contain a previously-unknown class of object, ultra-compact dwarf (UCD) galaxies. We present high resolution spectroscopy and deep multicolor imaging to show that these enigmatic objects are dynamically distinct from both globular clusters (GCs) and nucleated dwarf galaxies (dE,Ns). Our hypothesis for their origin may explain the observed high “specific frequency” of GCs in central cluster galaxies.

Thin films are used in micrometeoroid experiments to shield the sensors from external noise sources. Because of the spin of the Helios spacecraft the ecliptic sensor is exposed to the Sun. Therefore a 3000 Å parylene film coated on one side with 750 Å aluminium protects the experiment against UV-radiation and solar wind particles. The south sensor is shielded from solar emissions by the spacecraft rim and therefore has an open aperture.

A numerical method for 3D magnetohydrodynamical investigations of accretion disks in close binary systems is presented, which allows for good spatial resolution of structures (hot spot, accretion column). The gas is treated as individual gas cells (pseudo-particles) whose motion is calculated within a grid consisting of one spherical inner part for 3D MHD and two plane outer parts. Viscous interactions of the gas cells are taken into account by a special treatment connected with the grid geometry.

We present one result of 2D hydrodynamical calculations for a binary applying the following parameters which are representative for Cataclysmic Variables: M1 = 1 Mʘ, r1 = 10-2 Rʘ, M2 = 0.5 Mʘ, p = 0.2 d, M = 10-9 Mʘ y-1.

Column density and radiative flux distributions over the disk are shown and briefly discussed by comparison with the theoretical understanding of these Dwarf Novae drawn from observations.

We present the energy distribution of three hard X-ray sources H2252-035, 4U1849-31 and 2A0526-328 identified with intermediate polars. The ultraviolet and optical continuum can be well described by the standard disc model but this requires rather large discs and high accretion rates. Other possible contributions to the energy distribution are estimated. The predicted high accretion rates as well as the amplitude of the optical pulsations are in disagreement with the observed X-ray luminosity suggesting the existence of an unseen soft X-ray or extreme UV component.

The current observational and theoretical literature on Bok globules and their relationship to star formation is reviewed. Recent observations of globules at optical, infrared, and far infrared wavelengths are shown to provide important constraints on their structure and evolutionary status, and the suggestion that many globules are gravitationally unstable is seriously questioned.

Dark clouds associated with T associations are well-known sites of recent and continuing star formation. In recent years molecular observations and far infrared surveys have provided maps of such regions from which possible sites of star formation may be identified. Optical (Hα) and near infrared surveys have enabled a clear identification of pre-main sequence (PMS) objects within the clouds. Methods of distinguishing these from background objects and the nature of their infrared excesses are examined in the light of recent observations in the near and far infrared. The perennial question as to the existence of anomalous reddening within dark clouds is also investigated.

A series of VLBI surveys of complete samples of radio sources selected at 5 GHz (Pearson & Readhead 1988, hereafter PR; Xu et al. 1995 and references therein) has revealed that ≃ 10% of the objects are “Compact Symmetric Objects” (CSOs), in which high-luminosity radio emission regions are seen on both sides of the center of activity on scales less than one kiloparsec (Phillips & Mutel 1982; Readhead et al. 1984; Conway et al. 1992; Wilkinson et al. 1994). In order to be sure that an object is a CSO, either the center of activity must be pinpointed (Taylor et al. 1996) or compelling morphological evidence of symmetric structure must be found.

We present preliminary results of an analysis of X-ray and optical data of the asynchronous AM Her star BY Cam [1]. We use X-ray data from EXOSAT (0.1… 50 keV), Ginga (1.5… 50 keV) and ROSAT (0.1…2.0 keV) and optical data obtained during a 45-day campaign in 1994.

There are 4 known periods: the orbital period (201.30 m), the spin period of the white dwarf (199.3303 m), a spin-orbit beat period (14.15 d) and a side-band period (197.4 m). The detection of this side-band period lends credence to the theory of [2], who suggest that for a stream accreting, diskless, magnetic CV a frequency, f = 2ωspin − Ωorb (=197.399 m), will appear as a strong spike in the power spectrum for certain systems. Wu & Mason (this volume) discuss a competing model where Pspin = 197.4 m.

The Ciel, miroir des cultures poster-exhibition was designed by the Association Française d'Astronomie and printed in 300 copies in 2005. Each copy is composed of 14 posters introducing the different ways human beings and societies have used the sky and the heavens in history. More than three hundred cultural events have now been using the exhibition in schools and community structures as public libraries and social centres, taking place mainly in low-income urban or suburban neighbourhoods. This three-year work demonstrated the relevance of this kind of tools and events to pedagogical and social aims, specifically if the event is not limited to showing posters and also offers an opportunity for dialogue.

The National Observatory of Brazil was established in 1827 to study the problems of latitude and time. Time and latitude programs are still an important part of its work, but are now accompanied by increasing activity in the fields of geophysics, astrophysics and radio astronomy.

Spectroscopic observations are discussed which indicate that the winds of luminous OB stars are highly structured in space and variable in time. Blueward migrating discrete optical depth enhancements in the absorption troughs of P Cygni profiles are the characteristic signatures of the evolving structure. Constraints on physical mechanisms are discussed, provided by the observed accelerations of the migrating features, the evidence for rotationally modulated variability, and the behaviour of the winds at very low velocities.

At the IAU General Assembly in Patras in August 1982, Commission 33 set up a Working Group on the Galactic Constants. The Working Group is charged with developing a critical review of the values of the main galactic constants, for publication before the General Assembly in 1985. It has not been specifically charged to come up with a proposal for a revised set of values, although it can do so if it wishes.

From the fluctuations of the velocity and magnetic field observed in different kinds of solar wind the fluctuating electric fields are derived, and their power spectra are constructed and analysed. The mean electromotive force ɛ generated by the turbulent motions depends upon the nature of the fluctuations. Simple dynamo theory predicts a linear relationship between ɛ and the mean magnetic field B0. Correlation studies carried out to establish the alpha effect in the solar wind have given negative results.

Transitions of nuclear compositions in the crust of a neutron star induced by stellar spin-down are evaluated at zero temperature. We construct a compressible liquid-drop model for the energy of nuclei immersed in a neutron gas, including pairing and shell correction terms, in reference to the known properties of the ground state of matter above neutron drip density, 4.3 × 1011 g cm−3. Recent experimental values and extrapolations of nuclear masses are used for a description of matter at densities below neutron drip. Changes in the pressure of matter in the crust due to the stellar spin-down are calculated by taking into account the structure of the crust of a slowly and uniformly rotating relativistic neutron star. If the initial rotation period is of the order of milliseconds, these changes cause nuclei, initially being in the ground-state matter above a mass density of about 3 × 1013 g cm−3, to absorb neutrons in the equatorial region where the matter undergoes compression, and to emit them in the vicinity of the rotation axis where the matter undergoes decompression. Heat generation by these processes is found to have significant effects on the thermal evolution of old neutron stars with low magnetic fields; the surface emission predicted from this heating is compared with the ROSAT observations of X-ray emission from millisecond pulsars and is shown to be insufficient to explain the observed X-ray luminosities (Iida and Sato, 1997).