We present the results of optical photometry of the X-ray transient XTE J2123-058. CCD R-band images, have been obtained since 2 Jul until 29 Sep 1998. Following the behaviour of the XTE/ASM lightcurve, the system decline optically from the begining of August at approximately 0.1 mag/day. Despite the drop in luminosity, we observe a dramatic

A sample of 47 faint Gigahertz Peaked Spectrum (GPS) radio sources selected from the Westerbork Northern Sky Survey (WENSS) has been imaged in the optical and near-infrared, resulting in an identification fraction of 87 per cent. The R-IR-K colours of the faint optical counterparts are as expected for passively evolving elliptical galaxies

We have studied analytically the mean pull on shells of real (anisotropic and/or non-isolated) mass concentrations. Using a non-linear scheme, the radial component of the peculiar velocity is averaged over solid angle (V_0) and mass-averaged (V^*_0) for several different generic configurations. Nine Local Supercluster(LS)-like objects and six Great

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Nitrogen lines of the N I lambda1134 and lambda1200 multiplets in the damped Lyalpha (DLA) galaxies at z_abs = 2.309, 2.827, and 3.025 toward the QSOs 0100+1300, 1425+6039, and 0347-3819, respectively, have been detected by means of high-resolution spectra (R ~ 2 x 10^4) obtained with 4 m class telescopes at ESO (La Silla, Chile) and the

The first results of HST NICMOS observations of BL Lacertae objects are presented. Selected target, observed through the F160W filter, are from the HST "snapshot" survey of BL Lacs (Urry, Scarpa et al. 1999), span redshifts up to z=0.6. Observations provide reliable color information for the host galaxy, which in all cases is fully resolved. The