This book was conceived to commemorate the continuing success of the guest observer program for the International Ultraviolet Explorer (IUE) satellite observatory. It is also hoped that this volume will serve as a useful tutorial for those pursuing research in related fields with future space observatories. As the IUE has been the product of the three-way collaboration between the U.S. National Aeronautics and Space Administration (NASA), European Space Agency (ESA) and the British Engineering and Research Council (SERC), so is this book the fruit of the collaboration of the American and European participants in the IUE. As such, it is a testimony to timely international cooperation and sharing of resources that open up new possibilities. The IUE spacecraft was launched on the 26th of January in 1978 into a geosynchronous orbit over the Atlantic Ocean. The scientific operations of the IUE are performed for 16 hours a day from Goddard Space Flight Center in Greenbelt, Maryland, U.S.A, and for 8 hours a day from ESA Villafranca Satellite Tracking Station near Madrid, Spain.

ROSAT Observations G. HASINGER Max-Planck-Institut flir extraterrestrische Physik, D-85740 Garching, Germany Abstract. This review describes the most recent advances in the study of the extragalactic soft X-ray background and what we can learn about its constituents. The deepest pointed observations with the ROSAT PSPC are discussed. The logN-logS relation is presented, which reaches to the faintest X-ray fluxes and to the highest AGN surface densities ever achieved. The N(>S) relation shows a 2 density in excess of 400 deg- at the faintest fluxes and a flattening below the Einstein Deep Survey limit. About 60% of the extragalactic background has been resolved in the deepest field. Detailed source spectra and first optical and radio identifications will be discussed. The results are put into perspective of the higher energy X -ray background. Key words: X-rays, background radiations, active galactic nuclei. 1. Introduction The extragalactic X-ray background (XRB), discovered about 30 years ago, has been studied extensively with many X-ray experiments, in particular with the satel lites HEAO I and II (see ego Boldt 1987) and with ROSAT (e. g. Hasinger et aI. , 1993). Figure 1 shows a compilation of some of the most recent spectral measure ments for the X-ray background. Over the energy range from 3 to about 100 keY its spectrum can be well approximated by an optically thin thermal bremsstrahlung model with kT ~ 40 keY, while at lower X-ray energies a steepening into a new component has been observed observed (e. g.

A complete history of human endeavors in space, this book also moves beyond the traditional topics of human spaceflight, space technology, and space science to include political, social, cultural, and economic issues, and also commercial, civilian, and military applications. In two expertly written volumes, Space Exploration and Humanity: A Historical Encyclopedia covers all aspects of space flight in all participating nations, ranging from the Cold War–era beginnings of the space race to the lunar landings and the Apollo-Soyuz mission; from the Shuttle disasters and the Hubble telescope to Galileo, the Mars Rover, and the International Space Station. The book moves beyond the traditional topics of human spaceflight, space technology, and space science to include political, social, cultural, and economic issues, and also commercial, civilian, and military applications. Produced in conjunction with the History Committee of the American Astronautical Society, this work divides its coverage into six sections, each beginning with an overview essay, followed by an alphabetically organized series of entries on topics such as astrophysics and planetary science; civilian and commercial space applications; human spaceflight and microgravity science; space and society; and space technology and engineering. Whether investigating a specific issue or event or tracing an overarching historic trend, students and general readers will find this an invaluable resource for launching their study of one of humanity's most extraordinary endeavors.

A quick reference for the ultraviolet spectra of many categories of astronomical objects. Shows reflected sunlight from the Moon, planets, and asteroids, and emission from comets. Contains the spectra for: pre-main sequence stars, chemically peculiar stars, pulsating variables, subluminous stars, and Wolf-Rayet stars. Presents phenomena such as the chromospheric and transition region emissions from late-type stars; composite spectra of stars, gas streams, accretion disks and gas envelopes of binary systems; the behavior of gas ejecta shortly after the outburst of novac and supernovac; and the H II regions, planetary nebulae, and supernova remnants. Population 2 stars, globular clusters, and luminous stars in the Magellanic Clouds, M31, and M33, are included. Finally, gives the ultraviolet spectra of galaxies of different Hubble types and of active galaxies.

Readers of Freeman Dyson’s previous books, Disturbing the Universe, Weapons and Hope, and Infinite in All Directions, have discovered for themselves what Dyson reveals here: that he was a writer long before he became a distinguished scientist. The aim of this new book, as Dyson says, is to open windows, to let the experts inside the temple of science see out, and to let the ordinary citizens outside see in.” In this process an immensely broad range of ideas, people, contemporary history, and discoveries of many sorts pass in review. Beginning with a piece of writing he did as a child and ending with recent work, he goes from Eros, the god or youthful passion, to Gaia, the fertile life-giving mother-planet Earth. The pilgrimage is a good metaphor for the life of a writer. This book is full of discoveries. In the company of one of the most lucid minds of our time, one approaches great men and problems central to our common existence. Always there is warmth, kindness, high intelligence and humor. Dyson is intimate with both science and man. Whether he is dealing with the problems of physics or politics, whether he is engrossed in astronomy or literature, whether he is concentrating on an African village of space science, Dyson’s view is always “infinite in all directions,” always following the path of diversity, always keeping his eye on the wonder of our earth and the health and happiness of its inhabitants.