UV and EUV Instruments

TL;DR

This paper reviews the development and application of telescopes and instruments for astronomical research in the ultraviolet and extreme ultraviolet spectral regions, highlighting their technological differences and historical context.

Contribution

It provides a comprehensive overview of UV and EUV astronomical instruments, emphasizing their design, technological distinctions, and historical development.

Findings

EUV and UV instruments are based on different technological principles.

The wavelength ranges are defined by the hydrogen Lyman absorption edge.

Technological roots differ: EUV instruments relate to X-ray astronomy, UV instruments to optical astronomy.

Abstract

We describe telescopes and instruments that were developed and used for astronomical research in the ultraviolet (UV) and extreme ultraviolet (EUV) regions of the electromagnetic spectrum. The wavelength ranges covered by these bands are not uniquely defined. We use the following convention here: The EUV and UV span the regions ~100-912 and 912-3000 Angstroem respectively. The limitation between both ranges is a natural choice, because the hydrogen Lyman absorption edge is located at 912 Angstroem. At smaller wavelengths, astronomical sources are strongly absorbed by the interstellar medium. It also marks a technical limit, because telescopes and instruments are of different design. In the EUV range, the technology is strongly related to that utilized in X-ray astronomy, while in the UV range the instruments in many cases have their roots in optical astronomy. We will, therefore, describe the UV and EUV instruments in appropriate conciseness and refer to the respective chapters of this volume for more technical details.