We have taken deep R-band images of fields around five radiogalaxies: 0956+47, 1217+36, 3C256, 3C324 and 3C294 with 1 < z < 2. We found a statistically significant excess of bright (19.5 < R < 22) galaxies on scales of 2 arcmin around the radiogalaxies. The excess has been determined empirically to be at ≳99.5% level. It is remarkable that this excess is not present for 22 < R < 23.75 galaxies within the same area, suggesting that the excess is not physically associated to the galaxies but due to intervening groups and then related to gravitational lensing.

Many searches have been carried out to detect emission from massive primeval hydrogen clouds at high redshift. By observing the 21 cm line it has been possible to impose strong upper limits on the mass and number of protoclusters at high redshift (Wieringa, et al. 1992). Since strong Lyα emission is expected from primeval galaxies undergoing their first burst of star formation, many attempts to detect this emission have been made, but no positive detection has been reported, imposing strong constraints on models of galaxy formation (see Djorgovski et al. 1993 for a review).

We have carried out optical spectroscopic observations at intermediate spectral resolution of the massive high redshift radio galaxy 0902+34 at z ≈ 3.39. This source was first identified by Lilly (1988) (from hereafter L88). The study of high redshift radio galaxies is interesting to analyze the physical conditions of the early universe and the galaxy evolution at cosmological redshifts. It has been claimed that some of these systems may be protogalaxies in the process of formation. Indications for this are the flat spectrum and the absence of the 4000 Å break, features which have already been observed in many cases. In particular, observations in the spectral range from V to K suggest that 0902+34 is a young galaxy (Eisenhardt and Dickinson 1992). Recent radio observations of the 21 cm line of neutral hydrogen have detected (Uson et al. 1991) an absorption against the radio continuum source. This absorption could also leave a track in the optical, redwards the Lyα line. Our observations were carried out with the ISIS spectrograph at the 4.2 m William Herschel Telescope (seeing ≈ 1.2–1.6 arcsec). A spectral dispersion of 0.78 Å/pixel (blue arm) and 1.38 Å/pixel (red arm) was obtained. Å long slit of width 3′ was used providing a spectral resolution of ≈ 5.4 Å in the blue arm and of ≈ 9.5 Å in the red one. Both resolutions are a clear improvement over that achieved by L88 of 20 Å, allowing us to resolve the Lyα line (and its possible structure) and any other possible strong features appearing in the spectral range observed (e. g., C iv λ1549, He ii λ1640, …). Six different observations of 2700 s of the radio galaxy 0902+34 were carried out. The slit was rotated to coincide with the parallactic angle at the beginning of each exposure. This will allow us to map spectroscopically different regions of the galaxy (for more details see Martín-Mirones et al. 1994).

We compare galaxy counts in deep R-band exposures of the fields of 36 highly luminous, high redshift QSOs to those in control fields at a distance of 1 deg. We find indication for a weak overdensity of galaxies in the foreground of QSOs on scales of arcminutes on a low significance level. Counts inside rings around the quasars, stars in the quasar fields and stars in the control fields show evidence for an excess of galaxies on scales of several arcseconds around the quasars as well as for a stronger clustering of galaxies in the QSO fields than in the control fields. We interpret this in terms of an amplification bias by gravitational lensing.

we analyze the evolution of the luminosity function of galaxies using the CDM model in numerical simulations. There is an observational excess in the number counts of galaxies per square degree in the blur band Nb (i.e. APM, Maddox et al. 1990). Several authors have tried to reproduce it trying to fit the observations. Our model assumes an instantaneous star formation rate (SFR) proportional to a power of the local density. A ‘single star burst’ is produced each time step and we follow the evolution of the luminosity and colour of each ‘stellar group’. The galaxies are identified with a density criterium. We compute U,V,B,K colours and Nb and our results agree quite well with observations.

A new cosmological method and new calculations are presented in order to derive the cosmological fundamental parameters (H0, ω0, δ0) using the observed correlation function.

We perform statistical analyses in the CfA and SRC 2 catalogs regarding the dependences of galaxy morphology and galaxy circular velocity on enviroment.

In previous work (Anosova, Kiseleva 1993) we have studied the statistical properties of Hickson's (1982) compact galaxy groups. We have shown that most of these groups are confident and probable physical systems of galaxies. Only about 13% of galaxies can be non-members of their groups due to the effects of projection.

MST analysis shows the “Great Wall” as a statistically significant linear feature in the galaxy distribution. It is not as long as visual impressions may suggest. Another “Wall” extends radially, perpendicular to the GW. These two walls intersect at the Coma cluster.

A new catalog of superclusters from the entire sky cluster catalog of Abell et al. (1989) is compiled. In fact the last version of Reference Catalog of ACO Clusters of Galaxies (Kalinkov and Kuneva 1994) is used. The RC contains information of optical, radio and X-ray observations gathered from catalogs, lists and papers.

In our previous works (Anosova 1987, Anosova, Iyer, Varma 1994), we developed a new method for determination of the structure of a clustered distribution. In this work, we apply this method studying the observed distribution of galaxies in the Universe.

In our previous works (Anosova 1987, Anosova and Kiseleva 1993) we developed a new objective statistical method for an identification of members of star and galaxy clusters as chance or non-chance ones. In the case of galaxies this method uses simultaneously their radial velocities V and angular separations ρ.

Under the auspices of Sjur Refsdal, 25 astrophysicists and engineers from Germany and Scandinavia have founded a non-profit association, aiming at the use of an intelligent telescope for quasar monitoring in the optical (Borgeest et al. 1993). Beyond a better understanding of the physics in quasars, the scientific goals are determining the cosmic distance scale at large redshifts and constraining the nature of Dark Matter, both using the gravitational lens effect. Thus, targets of special interest are the multiply lensed quasars and some well-known violently variable blazars. The optical photometry will in part be carried out simultaneously to observations with, e.g., ISO, ROSAT, CGRO and various radio telescopes. For the first time, a complete quasar sample will be monitored continuously, namely a sub-sample of the all-sky 1 Jy catalogue (5 GHz). Since we will collect about 106 photometric data points during the programme, Megaphot has been chosen as name for the association. Members from Hamburg and Bochum intend to test the 1.5 m Hexapod Telescope (HPT) astronomically in the very near future. The HPT hardware was developed and built by Vertex Antennentechnik, Duisburg together with the Ruhr-Universität, Bochum and Carl Zeiss, Jena; the intelligent software and weather control requires still some work. When working well, the system will be placed at a site with excellent astronomical conditions. After a few years of exclusive quasar monitoring, it will be used as a German photometry telescope.

An accurate measurement of the primordial value of D/H would provide a critical test of nucleosynthesis models for the early universe and the baryon density. I briefly summarize the ongoing HST observations of the interstellar H and D Lyman-α absorption for lines of sight to nearby stars and comment on recent reports of extragalactic D/H measurements.

Gravitational lens system could form multiple images of the same radiating surface of a cosmic object. The radiation fluxes of these images interfere to one another (Refsdal, 1964). The practical importance of this effect is seems to be as follows: (i) it is the only direct test of microlensing (Schneider et al. 1985); (ii) this effect may say about fine structure of a lensed object; (iii) it must be allowed for simulations of microlensing process. The maximum effect is expected in the case when a cusp point of the microlensing caustic is projected on the lensed object. To investigate the interference effect in this case, the exact solution of the lens equation in the vicinity of the cusp point was obtained (Mandzhos, 1993): were ξ, η are dimensionless coordinates of a radiating element on the object plane; x, y are coordinates of the point at which the lens plane is intersected by light beam; furthermore: where is the lens scalar potential.

Applying the complex formalism of Part I we investigate the transformation of the ellipticity and orientation distribution of elliptical background sources by local lensing. One important result is that we can apply the techniques from Part I directly in most parts of the cluster field from which we can also reconstruct the distribution of the background sources, without further information. Knowing the distribution we can apply the techniques from Part I everywhere.

The long-term observational programme for investigation of quasar microlensing spectral effects was devised and now is implemented at the Special Astrophysics Observatory (Russia, N.Arkhys) and at the Astronomical Observatory of Kiev University (Ukraine, Kiev). The main goal of this programme is to study the fine quasar structure. For this purpose the observations of the gravitational lenses H1413+117 and Q2237+030 are carried out with the 6m SAO telescope in the integral field spectroscopy mode. The suitable equipment for such observations - the Multi-Pupil Field Spectrograph - was designed and built in SAO. From February 1993 several observations of each of these objects were performed. Here we present the preliminary results of the Clover Leaf observations on April 23/24, 1993. The quasar images are separated by angles nearly 1 arcsec. At seeing of the order of 1.5 arcsec the separation of the individual quasar image spectra was a problem. For this purpose a special procedure is developed. This procedure is based on the maximum likelihood hypothesis to restore a simple 4-point source picture plus the background. The effect of light scattering for a point source was simulated by means of observations of a reference star. Statistical properties of the radiation flux in question were studied by using the data of photon registration each 40 msec. The individual spectra of quasar images were obtained. The internal relative errors of the spectra separation procedure vary from 7 to 12% depending on wavelength. The spectra of quasar images 1, 2, 4 are not actually distorted. On the contrary, in the spectrum of the third image the profile of the emission line CIV differs considerably from the profile of the same line in the “undisturbed” quasar spectrum. Fig. 1a,b show the spectra of the 1st and the 3rd images.

We here present a short report about the application of a simple time delay estimator to the extensive data set compiled and partly observed by R. Schild, containing 707 A and B observations with corresponding error estimates from JD 244194 to JD 249169.

Gravitational microlensing, i.e. lensing by stars in a foreground galaxy, can affect not only the radiation flux observed from quasars (Chang and Refsdal, 1979) but also the spectral line profiles (Nemiroff, 1988; Schneider and Wambsganss, 1990). As a rule, in contrast to it, gravitational macrolensing, i.e. lensing by a whole galaxy or a cluster of galaxies, affects only the radiation flux; differences in image spectra arise mainly from source variability and travel time delays between images. However, if the source, the lens, and the observer are in motion relative to one another, then an additional shift in the source's image spectrum occurs due to the aberration of light (Birkinshaw and Gull, 1983; Khmil, 1988 and references therein). Here we consider the special case of intrinsic motions in the source and study their influence on spectra of macroimages.

In a recent study (Maoz and Grindlay 1995) we have found that a number of previously recognized anomalies in the diffuse x-ray background at soft energies (~0.5-2 keV) can be understood if about 20-30% of the diffuse flux arises from a population of low luminosity sources in a thick disk or flattened halo distribution in the Galaxy. Here we summarize our results and review the arguements that these objects are not accreting neutron stars or black holes but rather white dwarfs (i.e. CVs) which may have been produced in a primordial population of disrupted globular clusters.