We describe the ZEUS phasing camera for future extremely large telescopes (ELTs) based on the Zernike phase contrast method. A prototype instrument is under construction for implementation in the Active Phasing Experiment (APE), a VLT test bed scheduled for operation in 2007. The paper describes theoretical aspects of the method and its

Observations of M31 were obtained using the 0.8-m telescope at Wendelstein, Germany and the 1.2-m telescope at Calar Alto, Spain, over three observing seasons, from 2000 to 2003. Two broad-band filters, R and I close to Kron-Cousins system, were employed. (3 data files).

Astrometry and photometry for our target fields were acquired from observations for the ESO Imaging Survey (EIS) that used the Wide Field Imager (WFI) at the 2.2-m MPG/ESO telescope. The brightest targets in NGC 3293 and NGC 4755 were observed using FEROS at the ESO/MPG 2.2-m telescope on 2004 July 4-6. (4 data files).

Roque de los Muchachos Observatory (ORM) at La Palma (Canary Islands) is one of the two top sites selected for hosting the future European Large Telescope (ELT) (http://www.eso.org/projects/e-elt/), the other being Paranal (in Chile). Meteorological and seeing conditions are crucial for the site selection. New concepts related to geophysical

Context: .Observational follow-up programmes for the characterization of ultra-luminous X-ray sources (ULXs) require the construction of clean samples of such sources in which the contamination by foreground/background sources is minimum. Aims: .We calculate the degree of foreground/background contaminants among the ULX sample candidates in a

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