The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope: I. Overview of the instrument and its capabilities

We provide an overview of the design and capabilities of the near-infrared spectrograph (NIRSpec) onboard the James Webb Space Telescope. NIRSpec is designed to be capable of carrying out low-resolution ($R\!=30\!-330$) prism spectroscopy over the wavelength range $0.6-5.3\!~\mu$m and higher resolution ($R\!=500\!-1340$ or $R\!=1320\!-3600$) grating spectroscopy over $0.7-5.2\!~\mu$m, both in single-object mode employing any one of five fixed slits, or a 3.1$\times$3.2 arcsec$^2$ integral field unit, or in multiobject mode employing a novel programmable micro-shutter device covering a 3.6$\times$3.4~arcmin$^2$ field of view. The all-reflective optical chain of NIRSpec and the performance of its different components are described, and some of the trade-offs made in designing the instrument are touched upon. The faint-end spectrophotometric sensitivity expected of NIRSpec, as well as its dependency on the energetic particle environment that its two detector arrays are likely to be subjected to in orbit are also discussed

The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope: I. Overview of the instrument and its capabilities

We provide an overview of the design and capabilities of the near-infrared spectrograph (NIRSpec) onboard the James Webb Space Telescope. NIRSpec is designed to be capable of carrying out low-resolution ($R\!=30\!-330$) prism spectroscopy over the wavelength range $0.6-5.3\!~\mu$m and higher resolution ($R\!=500\!-1340$ or $R\!=1320\!-3600$) grating spectroscopy over $0.7-5.2\!~\mu$m, both in single-object mode employing any one of five fixed slits, or a 3.1$\times$3.2 arcsec$^2$ integral field unit, or in multiobject mode employing a novel programmable micro-shutter device covering a 3.6$\times$3.4~arcmin$^2$ field of view. The all-reflective optical chain of NIRSpec and the performance of its different components are described, and some of the trade-offs made in designing the instrument are touched upon. The faint-end spectrophotometric sensitivity expected of NIRSpec, as well as its dependency on the energetic particle environment that its two detector arrays are likely to be subjected to in orbit are also discussed

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Ultrasensitive Molecule Detection Based on Infrared Metamaterial Absorber with Vertical Nanogap

Surface-enhanced infrared absorption (SEIRA) spectroscopy is a powerful methodology for sensing and identifying small quantities of analyte molecules via coupling between molecular vibrations and an enhanced near-field induced in engineered structures. A metamaterial absorber (MA) is proposed as an efficient SEIRA platform; however, its efficiency is limited because it requires the appropriate insulator thickness and has a limited accessible area for sensing. SEIRA spectroscopy is proposed using an MA with a 10 nm thick vertical nanogap, and a record-high reflection difference SEIRA signal of 36% is experimentally achieved using a 1-octadecanethiol monolayer target molecule. Theoretical and experimental comparative studies are conducted using MAs with three different vertical nanogaps. The MAs with a vertical nanogap are processed using nanoimprint lithography and isotropic dry etching, which allow cost-effective large-area patterning and mass production. The proposed structure may provide promising routes for ultrasensitive sensing and detection applications

Numerische Lösung von Warteschlangennetzwerken auf Pipelinerechnern

Ein Rechensystem bearbeitet Aufträge.. Eine Beurteilung der Art und Weise und der Effizienz ist auf verschiedenen Wegen möglich. Als Hilfsmittel wird hier ein Warteschlangenmodell des Rechensystems herangezogen.. Die Vorgänge in diesem Modell, von denen angenommen wird, daß sie solche des realen Systems annähern, sind durch Ubergangswahrscheinlichkeiten bzw. -raten von einem Zustand des Modells in einen möglichen Folgezustand beschreibbar. Bei sinnvoller Anordnung dieser Raten oder Wahrscheinlichkeiten in Form einer Matrix sind zur Bestimmung eines Gleichgewichtszustands des Modellsystems numerische Methoden anwendbar. Die Warteschlangenlängen, durchschnittliche Verweildauer eines Auftrags im System etc. können dann leicht berechnet werden. Die Gestaltung des Modells und die Auswahl der numerischen Verfahren erfolgte anhand der Dissertation von B. Müller (MUE 80). Teile dieser Verfahren scheinen für einen Pipelinerechner geeignet zu sein. Weil Warteschlangennetzwerke der hier betrachteten Form zwar einen endlichen, aber im allgemeinen sehr großen Zustandsraum haben, verspricht die Verwendbarkeit eines Pipelinerechners eine wesentliche Verkürzung der Rechenzeit auch für Algorithmen zur Lösung solcher Probleme. Im Kapitel 2 werden die Grundlagen des Pipelining skizziert, ein Uberblick über Aufbau und Funktionsweise des verwendeten Rechners gegeben und die verwendete Hilfssoftware genannt. Das 3. Kapitel beschäftigt sich mit den mathematischen Grundlagen der verwendeten Verfahren aus der Wahrscheinlichkeits- und Warteschlangentheorie sowie, im Anschluß, mit der Schilderung der numerischen Verfahren selbst. Eine Klasse von Warteschlangennetzwerkmodellen wird im 4. Kapitel ausführlich beschrieben. Dabei wird die Verbindung zu den im vorigen Kapitel aufgeführten Methoden hergestellt und die für diese Verfahren wesentlichen Eigenschaften der Modellklasse genannt. Alle vorgenommenen Vereinfachungen des Modells sind erwähnt. Es schließt sich das Kapitel über die Algorithmen selbst an. Dort findet man im wesentlichen einen Uberblick über die benutzten Datenstrukturen und die Einzelbeschreibung der Programme. Den letzten Punkt bildet eine qualitative Schilderung der Testläufe unter Skizzierung der jeweils dafür notwendigen Änderungen

A timesharing benchmark on an IBM/370-168

For the preparation of a planned exchange of an IBM/370-158 CPU with an 168 CPU, a benchmark was run. Five different configurations were investigated using two types of benchmark scripts and the two timesharing operating systems, OS/VS2 Rel. 3 and TSS/370 Rel. 2. The description of the measurements and the results are presented