Using available optical and X-ray catalogues of clusters and superclusters of galaxies, we build templates of thermal Sunyaev-Zel'dovich (tSZ) emission as they should be detected by the WMAP experiment. We compute the cross-correlation of our templates with WMAP temperature maps, and interpret our results separately for clusters and for

We have conducted a detailed study of the open clusters NGC 2451 A and B which are located along the same line of sight at 206pc and 370pc distance respectively. Although belonging to the nearest clusters they have not been much investigated until present due to strong contamination by field stars. ROSAT X-ray observations and optical UBVR

We present a photometric survey of bright southern stars carried out using the DENIS instrument equipped with attenuating filters. The observations were carried out not using the survey mode of DENIS, but with individual target pointings. This project was stimulated by the need to obtain near-infrared photometry of stars to be used in early

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We present emission line mapping of the strongly barred galaxy NGC 1530 obtained using Fabry-Pérot interferometry in Halpha, at significantly enhanced angular resolution compared with previously published studies. The main point of the work is to examine in detail the non-circular components of the velocity field of the gas, presumably induced by

What do we understand of the birth and death of stars? What is the nature of the tiny dust grains that permeate our Galaxy and other galaxies? And how likely is the existence of brown dwarfs, extrasolar planets or other sub-stellar mass objects? These are just a few of the questions that can now be addressed in a new era of infrared observations