I believe it is very difficult to make any recommendations or give any advice for site survey expeditions except of a very general nature. When you start out anew, then, as Dr. Scorer has already stressed very strongly, the first thing you have to do is to contact the meteorological office or the local meteorologist. There is no need to go into detail for I think you all realize that the statistics presented by the weather bureau do not serve our purpose. They are made for a different purpose than ours, and you will always have to go back to the original records and pull out from them the data that may be useful. Suppose you have done this, and you have located either on a world-wide scale the country that is the most promising, or within the country the most promising place as far as cloudiness is concerned. Then what are the next steps ?

We have made a preliminary map of the Horsehead nebula in CO (J=1-0) using the NRO 45-m telescope. The HPBW is 15″, the grid spacing 10″, and the velocity resolution is ∼0.1km/s. Figure 1 shows the integrated intensity with a velocity interval 10-11.5 km/s, which we found represents well the shape of the dark globule of the Horsehead. The coincidence of the CO feature and the dark nebulocity is strikingly well, especially at the sharp edges in the south and in the west (from the neck to the ears). The quality of the data are not satisfactory, though. The typical noise level is 1 K rms in TA, and the accuracies of the pointing and the intensity calibration is rather low due to the bad weather during the observation. Some scanning effects in the intensities can be recognized in Figure 1. One of the reason why the gap obtically seen beneath the jaw is not clear in the CO map may be attributed to the pointing errors.

A rocket payload is being prepared for the purpose of examining the spatial distribution of line emission from two important ions, Ovii and Neix, in the solar corona. The payload will contain the following integrated set of instruments.

(1) A pair of X-ray spectrometers utilizing KAP crystals of approximately 100 cm2 area.

(2) An optical aspect camera with a 1 Å bandpass H-α filter to measure the location of the field of view of the X-ray systems on the sun through out the rocket flight.

(3) A collimated proportional counter spectrometer operating in the 3 to 15 keV range.

The extragalactic background at ultraviolet, X-ray and gamma ray energies is reviewed. Early work on the diffuse backgrounds in each of these bands was motivated, at least in part, by the idea that these fluxes were the result of processes which produced a truly diffuse flux with profound cosmological implications. As we will see, these processes were not observed. However, the study of this background has led to the discovery of unexpected processes at work in the Universe. Our current understanding of these backgrounds is presented.

The previous reports by Lüst and by Pottasch concerned quasi-stationary mass loss. The loss is called quasi-stationary because the basic characteristics of a star, its temperature and its radius, do not change significantly during the time that a particle needs to flow from the stellar surface out to a point where the stellar influence is negligible. However there are many stars which show significant changes of temperature and radius within a short time. Very often these changes are accompanied by instantaneous ejection of a great amount of material. For example, during the outburst of a nova the ejected mass can reach 10−4M⊙. Such effects are very appreciable in the so-called ‘eruptive variables’, in which the brightness changes spasmodically. It is very likely that the rate and the mechanism of mass loss of eruptive variables are different from that of normal stars.

Increased sophistication in both, direct impact detectors and zodiacal light measurements encourages to discuss the compatibility of the results obtained by these quite different methods of investigating interplanetary dust. Taking recent measurements of particle fluxes and velocities obtained by the space missions of Pioneer 8/9 (Berg and Grün 1973), Heos 2 (Hoffmann et al. 1975), and comparing them with submicron-sized craters on lunar surface samples (Schneider et al. 1973, Fechtig et al. 1974) there seem to be two types of interplanetary dust populations: larger (>10−12 g) micrometeorites orbiting around the sun as the classical zodiacal dust cloud and a second component of very small (<10−12 g) particles coming radially from the direction of the sun with high velocities (>50 km/s). On the basis of the flux data referred to above and adopting for both components velocities of 10 or 50 km/s relative to the detector, respectively, a differential distribution function n(a) · da was found for the particle radii (a) as shown at a logarithmic scale in fig. 1. A density of 3 g/cm3 was adopted in order to convert particle masses into radii. The regions A, B, C (see Table 1) correspond approximately to the regimes of “submicron particles”, the classical zodiacal cloud particles, and the meteoritic component of the interplanetary dust complex. From this information the brightness I(ε) of the zodiacal light in the ecliptic plane can be computed as a function of elongation by approximating the distribution function n(a) in the different regions by simple power laws a−k ·da and by adopting a resonable scattering function σ(θ) for the average scattering behaviour of one particle of the mixture depending on the scattering angle θ. By use of an inverse (v = 1) decrease of particle number densities n = no · r−v with solar distance r(AU), where no is the number density at r=1 AU, one obtains with a particle size distribution law n(a)da ~ a−k da in the different intervals of sizes (Table 1) the intensity of the zodiacal light (in stars of 10th magnitude per square degree, S10) as shown in fig. 2. The two models (Maximum, Minimum) correspond to an upper and to a lower limit of particle number densities compatible with the in situ measurements, respectively.

The NOAO Survey for Ionization in Neutral Gas Galaxies (SINGG) is the largest star formation survey of an H I selected sample. Since the selection is made without regard to optical morphology, it is not biased toward or against “interesting” types of galaxies; thus SINGG is an ideal sample for studying galaxy demographics. Of a sample of 90 extra-galactic sources observed in photometric conditions, all are detected in Hα. This indicates that dormant galaxies, those containing an appreciable ISM but no star formation, are at best rare. We have made first pass morphological surveys for starbursts, as judged by Hα surface brightness, and outflows as judged by extra-planar Hα. We find that about 15% of the sources contain starbursts, with little dependence on the neutral hydrogen mass MHI. Nearly one half of a sample ~ 35 edge-on galaxies show evidence for extra-planar Hα having a scale size of 0.5 Kpc or larger, while nearly one quarter have extra-planar Hα features 1.0 Kpc in size or larger. There is a hint that high MHI systems preferentially have displaced outflows (chimneys, or fountains) while central outflows (galactic winds) preferentially occur in low MHI systems. However, a larger sample (e.g. the full SINGG survey) is needed to confirm this trend.

On résume l’ensemble des décalages vers le rouge dont on dispose à partir de la raie 21 cm. La plus grande valeur obtenue pour la raie HI en émission est z =0.0369, et z = 0.692 en absorption. Il y a un excellent accord avec les décalages vers le rouge mesurés optiquement (lorsqu’ils existent). Les deux techniques donnent la même valeur (en moyenne), et montrent que les décalages vers le rouge sont indépendants des longueurs d’onde dans un intervalle de longueur d’onde de ~5x105 et un intervalle en z de -0.0012 à +0.692. C’est une condition nécessaire, mais non suffisante pour interpréter les décalages vers le rouge par l’effet Doppler. Des limites sont fixées pour la variation possible de certaines constantes atomiques fondamentales en fonction de z, et si z est une mesure de la loi d’expansion de Hubble, en fonction du temps, jusqu’à des temps au moins égaux à 35% de l’âge de l’Univers.

Over 20000 thermal emission spectra of Mars have been obtained, providing extensive diurnal, seasonal and spatial coverage of the planet. Each spectrum covers the spectral range from 200 to 2000 cm−1 with an apodized spectral resolution of 2.4 cm−1; the noise equivalent radiance of the instrument is 0.5 × 10−7 W cm−2 sr−1 (cm−1)−1.

We present Doppler images of the accretion disc in the black hole X-ray transient V404 Cyg during its quiescent phase. The Hα map shows evidence for a hot spot, indicating that mass transfer is continuing long after the 1989 outburst. Both the Hα and the IR Ca II emission maps exhibit intense bright spots at the position of the secondary star, which we take as a sign of chromospheric activity. The Ca II emission arises from the outer parts of the accretion disc, and its surface brightness distribution is consistent with dwarf novae discs (I∝R−3/2).

First, I should like to say something about the use of highly specialized models in cosmology. The Einstein—de Sitter model is a relativistic model in which the cosmical constant and the space-curvature constant are both equated to zero. Likewise, the pressure is assumed to be zero throughout the history of the universe, except perhaps at the initial instant. It is well-known that the first two constants can be determined from observation, if not at present, at any rate as the data are refined in the future. Hence, I think it is a weakness to prejudge the issue and assign a priori values. Nor is it self-evident to me that the pressure must always have been zero even if it is zero now. Composite models, with nonzero pressure at first, followed by a zero-pressure condition, need to be examined.

In view of the spectral similarity and the probable evolutionary relation between certain planetary nebulae (PN) and other objects that are generally binaries (symbiotic stars, Be stars, or slow novae), it is probable that many nuclei of PN are double.

While trying to determine the rotation curve in 1953 Kwee, Muller, and Westerhout [1] found long and faint wings in the line profiles within 20 to 25 degrees longitude from the center. The gas responsible for these wings should therefore lie within 3 kiloparsecs from the center. The velocities of the neutral hydrogen causing these wings are far greater than could be expected on the basis of a reasonable rotational model of the Galaxy. Therefore, the wings were tentatively interpreted as being caused by high turbulent velocities in the gas. In view of the new and better data obtained with the 25-meter telescope in Dwingeloo, this interpretation has now been dropped. The new conclusion is that all of the neutral hydrogen in these regions is expanding and at the same time taking part in the galactic rotation. The evidence for this conclusion will be briefly presented.

Using Hipparcos and Tycho-2 data, together with the radial velocity information, a statistical analysis is applied to all the orbital solutions of planetary candidates, in order to avoid a bias towards small inclinations. There are hints of additional, longer period companions.

We present the results of X-ray and millimetre monitoring of the blazar 3C273 at 1–2 day intervals over the period 12 December 1992 to 24 January 1993. No large flares are seen in this period but variations in both wavebands of ∼ 30% on few day timescales are apparent. The ROSAT PSPC X-ray spectrum consists of 2 power-law components with the harder component dominating above 0.5 keV. There is very little correlation between the variability of the soft and hard components. The soft component does not correlate with the millimetre variations, but the hard component correlates reasonably well and leads the millimetre variations by about 10 days. These results show that the hard X-ray component cannot be a simple extrapolation of the millimetre/IR synchrotron component but may be explained as a self-Compton component in a shocked jet.

Sanduleak and independently Seggewiss discovered a very red star near the open cluster NGC 6231. Bessell and collaborators concluded it to be a variable of the R Coronae Borealis type.

A pair of spectrograms of this object were obtained in July 1970. The spectrograph dispersion in the range of 3800–4500 Å is around 80 Å mm−1 and in the range of 4500–7000 Å 155 Å mm−1.

An outstanding feature of the spectrograms is their ‘veiled’ aspect, making it rather difficult to observe the lines. We observe the 4226 Å of Ca I, H and K of Ca II, 4030/4034 Å of Mn I, the G band; and several lines belonging to the Fe I multiplets. The Hα and Hβ lines are clearly seen in emission. Hδ is absent or very faint. A spectrogram of RY Sagitarii taken in July 16, 1971, when the visual magnitude of the star was around 4 mag. below its maximum light, shows some similarities with the spectrograms of the Sanduleak-Seggewiss star, e.g. they do not show the ultraviolet CN absorption bands and in the spectra of both stars a line is seen at approximately 3896 Å, which may be H8.

If we accept that the star belongs to NGC 6231, its distance modulus is 11.5. Its intrinsic color may be assumed to be close to (B–F)0 = 1.0(G or K star). The observed color is (B–K) = 3.5. Adopting R = 3, the visual absorption is 7.5. As the visual magnitude of the star is V= 12.5, its absolute magnitude becomes – 6.5.

Details will be published elsewhere.

The various mechanisms whereby stars might lose matter are considered, together with the observational evidence of the mass loss rates associated with these mechanisms. The results are shown in a diagram giving the fractional mass that a star loses by various mechanisms as a function of initial mass.

The stability of the three-body problem formed by the Sun, Jupiter and Saturn is investigated using surfaces of zero velocity. The results obtained with the models of the restricted and general problems of three bodies are compared with numerical integration. The system is found to be stable in the sense that Saturn will neither interrupt the (perturbed) binary orbit of Jupiter around the Sun, nor will it escape from the system. It is shown that the known classical triple stellar systems are “more stable” than the solar system, which in turn is “more stable” than the Earth-Moon system.