70 research outputs found
The James Webb Space Telescope Mission: Optical Telescope Element Design, Development, and Performance
The James Webb Space Telescope (JWST) is a large, infrared space telescope
that has recently started its science program which will enable breakthroughs
in astrophysics and planetary science. Notably, JWST will provide the very
first observations of the earliest luminous objects in the Universe and start a
new era of exoplanet atmospheric characterization. This transformative science
is enabled by a 6.6 m telescope that is passively cooled with a 5-layer
sunshield. The primary mirror is comprised of 18 controllable, low areal
density hexagonal segments, that were aligned and phased relative to each other
in orbit using innovative image-based wavefront sensing and control algorithms.
This revolutionary telescope took more than two decades to develop with a
widely distributed team across engineering disciplines. We present an overview
of the telescope requirements, architecture, development, superb on-orbit
performance, and lessons learned. JWST successfully demonstrates a segmented
aperture space telescope and establishes a path to building even larger space
telescopes.Comment: accepted by PASP for JWST Overview Special Issue; 34 pages, 25
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Anti-Semitic Stereotypes without Jews
Anti-Semitic Stereotypes Without Jews offers an exploration of English history, 1290- 1700, tracing the growth and development of these attitudes. It demonstrates that it is possible for prejudice to thrive even in the absence of a scapegoat group. Following the expulsion in the year 1290 until 1656, although there was no real Jewish community in England, the molders of public opinion kept a shadowy image of the Jew alive through sermons and religious tracts, travelogues, folklore, religious and secular drama. In his analysis, Dr. Glassman shows that despite their theological differences, Anglican, Puritan, and Catholic clergymen concurred in the negative images of Jews presented to their congregations. They pictured the Jews as Christ-killers, and related myths of how Jews performed barbaric and sacrilegious rituals. The image was to plague Anglo-Jewry after a small community was reestablished in the second half of the 17th century. The author's belief that anti-Semitism is primarily a Christian problem transcends both time and place is covered by this volume. Anti-Semitic sentiments are seen here as reflecting deep-seated, irrational responses to the Jewish people, rooted in the teachings of the church and exploited by men who needed an outlet for religious, social, and economic frustrations
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