This paper defines the UKIRT Infrared Deep Sky Survey (UKIDSS) Early Data Release (EDR). UKIDSS is a set of five large near-infrared surveys being undertaken with the United Kingdom Infrared Telescope Wide Field Camera (WFCAM). The programme began in 2005 May and has an expected duration of 7yr. Each survey uses some or all of the broad-band filter

The Universe at Large presents a unique survey of key questions outstanding in contemporary astronomy and cosmology. In this timely volume, eleven of the world's greatest living astronomers and cosmologists present personal views of what problems must be addressed by future research. Allan Sandage presents a 23-point plan to reach a full

The Universidad Complutense of Madrid (UCM) has recently installed a high sensitivity video system to detect meteors. It is intended to study the entry in our atmosphere of interplanetary particles of mass greater than a gram. The station, not fully equipped yet, is a node of the national Spanish Fireball Network (SPMN) and includes cameras located

For the first time, we explore the dynamics of the central region of a galaxy cluster within r 500 ∼ 600 h‑1 kpc from its center by combining optical and X-ray spectroscopy. We use (1) the caustic technique, which identifies the cluster substructures and their galaxy members with optical spectroscopic data, and (2) the X-ray redshift fitting

It is planned to include adaptive optics as an integral part of the 10-m Gran Telescopio Canarias. Preliminary scientific requirements have been drawn up, and it is necessary to identify systems which will satisfy these requirements. The approach adopted here is to use the LACE program to model the adaptive-optics system. The program provides for

The study of iron lines from 49 high-resolution IUE spectra observed in the period of 1985-1991 allowed us to find a repetition time between two successive shells of the order of six months. We found that absorption lines of Fe III often have two components while Fe II lines can have three. P Cygni is the only luminous blue variable that does not