We present a cross-correlation between the European Large Area ISO Survey (ELAIS) 15-μm ISO survey with the ROSAT (0.1-2keV) all-sky survey and the pointed observations WGACAT source catalogue. The resulting sample contains 15 objects. Optical spectroscopic identifications exist for 13 objects: six broad-line quasi-stellar objects (QSOs), four

Conference was held in La Palma, Spain in 2001 May. Proceedings have been edited by J. H. Knapen, J. E. Beckman, I. Shlosman, & T. J. Mahoney and published in the ASP Conference Series, Vol. 249 (2001).

Deep extragalactic surveys with ISOCAM revealed the presence of a large density of faint mid-infrared (MIR) sources. We have computed the 15 mu m integrated galaxy light produced by these galaxies above a sensitivity limit of 50 mu Jy. It sets a lower limit to the 15 mu m extragalactic background light of (2.4 +/- 0.5) nW m-2 sr-1. The redshift

The evolution of the morphology of C/1999 S4 (LINEAR) is examined from a series of images taken from shortly before the disruption of the nucleus until 10 days afterwards. This is combined with light curve data to provide a unique documentation of the early evolution of the disruption event. Neither images from the 1-m Jacobus Kapteyn Telescope nor

We provide constraints on the AGN contribution to the mid-IR extragalactic background light from a correlation analysis of deep X-ray and mid-IR observations in two regions centred on the Lockman Hole and Hubble Deep Field North (HDF-N). The Lockman region, of more than 200 square arcminutes, was observed by ISOCAM and XMM-Newton to a depth of 0.3

The goal of this work is two-fold. In the first part of this paper we regard classical Plebanski's action as a BF action supplemented by constraints. We introduce a spin foam model for Riemannian general relativity by systematically implementing these constraints as restrictions on paths in the state-sum of the BF theory. The spin foam model