The XMM-LSS survey. Survey design and first results

We have designed a medium deep large area X-ray survey with XMM - the XMM Large Scale Structure survey, XMM-LSS - with the scope of extending the cosmological tests attempted using ROSAT cluster samples to two redshift bins between 0<z<1 while maintaining the precision of earlier studies. Two main goals have constrained the survey design: the evolutionary study of the cluster-cluster correlation function and of the cluster number density. The results are promising and, so far, in accordance with our predictions as to the survey sensitivity and cluster number density. The feasibility of the programme is demonstrated and further X-ray coverage is awaited in order to proceed with a truly significant statistical analysis. (Abridged)Comment: Published in Journal of Cosmology and Astroparticle Physic

Orientation des p5les d'ast roomegades

SIGLEBSE B226311X / UCL - Université Catholique de LouvainBEBelgiu

The GL bibliography and an interactive database (Poster contribution)

It is now possible to directly access, via the Internet, a bibliographical database on Gravitational Lensing (GL) literature. The Interactive Gravitational Lensing Bibliography (IGLB) totalizes more than 2400 titles of published articles in scientific journals and meeting proceedings (except those fully dedicated to Gravitational Lenses) as well as papers submitted to the e-Print archive. This database is a product from the Gravitational Lensing Bibliography first presented in 1993 (Proceedings of the 31st Liege International Astrophysical Colloquium). It is easy to do field based searches for title keywords, authors (using boolean operators), year and journal (a pull-down list of the most cited journals is available). Access to the original version of published articles as well as to preprints submitted to the e-Print archive at the URL address http://xxx.lanl.gov/ is also provided. This database is updated approximately every two months. The "complete" bibliography of published articles is also available in the form of Latex and PostScript files. The IGLB can be accessed at the URL: http://vela.astro.ulg.ac.be/grav_len

Determination of the Spin Axis Orientation of Asteroids: Inversion of Photometric Lightcurves

peer reviewe

Further observations of the light echoes from SN 1987 A

Further direct observations of the light echoes from SN 1987 A were obtained on November 12 1988 with the 3.6-m telescope and EFOSC at ESO. In agreement with predictions made from earlier observations, the radii of the two light rings are measured to be 43.3 and 72.5 arcsec. However, a noticeable diaplacement of the center of the outer ring by 2.6 arcsec to the NE from the SN position is also reported. Application of the model of planar-like sheets of material located between the SN and the observer leads to improved results

Determination of the Spin Vector of a Synthetic Asteroid

peer reviewe

Pole, albedo and shape of the minor planets 624 Hektor and 43 Ariadne: Two tests for comparing four different pole determination methods

Asteroids 624 Hektor and 43 Ariadne have been observed photometrically at the European Southern Observatory (La Silla, Chile) in order to determine their pole orientation. The lightcurves (1984 and 1991 oppositions for Hektor, and 1985 for Ariadne) are presented. Some of the traditional pole determination methods have been improved, and completely original ones have been developed. They are described and applied to the newly recorded and previously published light curves. The results are commented and compared with previous ones. In addition to the pole orientation, we also derive some information on the shape or the albedo distribtuion of the objects. With the aim of optimizing future observations of these asteroids, we present some graphs showing the best longitudes where they should be measured. Finally, we suggest some improvements in the pole determination and modeling methods based upon photometric data