C. Stuart Bowyer

A far ultraviolet photometer for space research

Abstract A photometer for use in the wavelength region from 100 to 1300 A has been developed. Specific bands within this region can be isolated by combining the spectral response of individual solar blind photocathodes with the transmission qualities of various thin metallic films. A continuous channel electron multiplier is used as a low background, high gain charge amplifier in the device. Each of these components is discussed in turn with emphasis placed on those characteristics which have special relevance to space borne instrumentation. Two examples of instruments employing these components are given, one a device to measure the resonantly scattered hydrogen and helium radiation in the upper atmosphere, and the other a device to measure the far u.v. photon flux generated in an aurora.

The Extreme Ultraviolet Explorer: overview and calibration

The Extreme Ultraviolet Explorer (EUVE) is a NASA-funded astronomy mission that will operate in the 70 to 760 A band. The science payload# which has been designed and built by the Space Sciences Laboratory at the University of California, Berkeley, consists of three grazing incidence scanning telescopes and an EUV spectrometer/deep survey instrument. We give details of the planned mission profile and an overview of the instrumentation that the science payload comprises. Topics such as the thermal design, contamination control, and details of the electronics system are discussed. Finally, we review the results of the calibration of the various subsystems that make up the EUVE instrumentation and discuss the calibration plan for the integrated EUVE instruments, which began in June 1989 at the Berkeley EUV Calibration Facility.

Design of spherical varied line-space gratings for a high-resolution EUV spectrometer

A highly efficient EUV spectrograph is designed for high-resolution spectroscopic observation. The spectrograph is designed for point source astronomy in a 40-120 nm bandpass and is to be ORFEUS (Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer), scheduled for launch as the first payload of a German space platform Astro-SPAS (Astronomy Shuttle Pallet Satellite). The design uses spherical varied line-space (SVLS) grating to minimize astigmatism, coma, and spherical aberration. The effectiveness and practical feasibility of the design is proved by an SVLS grating for visible use. The image focusing properties of the SVLS grating for ORFEUS are compared to those with toroidal uniform line-space (TULS) design. The SVLS design is superior to the TULS, theoretically in resolution and image concentration, but also practically with not only fabrication ease. Four SVLS gratings with nominal groove densities of 6000, 4550, 3450, and 2616 gr./mm, and a 200 mm x 200 mm ruled area have been ruled using a numerically controlled ruling engine for use in ORFEUS.

Unique variable line-space spectrometers on the EUVE satellite: in-flight performance and selected scientific results

Until recently, spectrometer designs for use at extreme ultraviolet wavelengths have been limited to grazing incidence Rowland spectrometers and transmission gratings. In principle, the new class of variable line-space spectrometers offer substantial advantages over these classic designs. The Extreme Ultraviolet Explorer Satellite has three variable line-space spectrometers as part of its scientific complement; this is the first use of this class of device. The results obtained have been quite noteworthy. The in-orbit performance of these spectrometers are demonstrated with examples of the scientific results obtained in this mission.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Berkeley EUV spectrometer microchannel plate detectors for ORFEUS

We have developed detectors design for high resolution spectroscopic imaging for the EUV spectrometer on the ORFEUS-SPAS mission. The detectors employ spherically curved microchannel plates and a delay line read out system. We present results from the testing and calibration of the detectors prior to their integration into the spectrometer. The design, MCP preconditioning, and imaging characteristics are discussed for 2 rectangular spectral detectors and for the fine guidance detector. Each spectral detector achieves a 30 X 100 micrometers FWHM resolution element size over a 95 mm X 25 mm anode format with good linearity (< 30 micrometers ) in the spectral direction. The fine guidance detector, used for drift corrections, achieves good resolution and will meet the necessary centroiding requirements.

Grazing incidence optics in extreme-ultraviolet astronomy

ABSTRACT The developmeni of grazing incidence opiics for exireme uUraviole (EUV) astronomy occurred in a vas1lydiffereni science-poliiical environmeni Than ha of X-ray astronomy. X-ray asfronomy had been proven asan exiremely usefulfield ofresearch, and in The environmeni ofihe 1960s funds were available for X-ray glassmirror sysiems costing lens of millions of dollars for a single lelescope. In thai era, EUV asironomy hadnoi ye been demonsiraied as a viable field, and indeed, the general belief was iha only a few asironomicalsources would be observable in this band. In ihal environmeni there was no hope of obiaining funding forEUV lelescopes similar lo ihose used in X-ray asironomy. As a consequence, an enlirely differeni approachwas employed in the developmeni of EUV grazing incidence oplics.The general approach was lo ailempi lo make grazing incidence EUV opiics out of melal. In the end, ihebesi of ihese oplics were as good as the X-ray glass optics developed for the Einstein Observatory, but witha cost of 1/20 of the Einstein mirrors.The various technologies developed in order to carry out EUV astronomy are discussed with an emphasison EUV grazing incidence mirrors. A report of a few of the astronomical results obtained through the useof these optics are presented.Keywords: grazing incidence optics, extreme ultraviolet telescopesIn this paper I provide a brief overview of the technical developments that made extreme ultraviolet (EUV)astronomy a reality with special emphasis on the development of extreme ultraviolet grazing incidence mirrors. Thisis an especially delightful task given the fact that some thirty years ago it was generally believed that no research

Diffuse EUV spectrometer UCB

An extreme ultra-violet diffuse spectrograph known as the ultraviolet cosmic background spectrometer is scheduled for a 1996 launch on the NASA SSTI mission Lewis. UCB is one of three prime science instruments aboard the Lewis spacecraft and is schedules to conduct observations for 3 to 5 years. The spectrograph will obtain spectra of diffuse 550 to 1100 angstrom radiation with a sensitivity improvement of an order of magnitude or more in comparison with previous work. UCB incorporates new technology such as a special diffraction grating, an anti-coincidence guarded micro- channel plate detector system, low-radioactivity ultra low- noise micro-channel plates, and a chemical treatment for enhancing detector efficiency. The observations will contribute important new information about the Galaxys local interstellar medium and about speculative scenarios regarding exotic nuclear particles in dark matter. We describe the instrumentation and the UCB science mission.

Radio searches for large-scale extraterrestrial organisms

A variety of means can be employed to search for extraterrestrial life. Large-scale extraterrestrials are reasonably expected to have developed intelligence (since intelligence is selectively advantageous) and technology (since technology also provides advantages). In the expectation/hope that more advanced extraterrestrials will be sending an announcement signal to help us make contact and share in our galactic heritage, more than 30 radio searches have been carried out over the last 40 years. Current searches are up to 4 orders of magnitude more sensitive and cover up to 108 more bandpass than the original searches. An overview of the rationale behind these searches and the current status of this work is provided.

SERENDIP SETI project: new instrumentation for SETI and results of the recent Arecibo sky survey

The SERENDIP SETI group is currently conducting search operations on the worlds largest radio telescope at the Arecibo Observatory in Puerto Rico. The third generation SERENDIP system, SERENDIP III, is a 4 million channel Fast Fourier Transform-based spectrum analyzer with 0.6 Hz frequency resolution. In this talk we will discuss results of our recent 3.5 year sky survey. SERENDIP has looked at 95 percent of the sky visible from Arecibo in the range from 424 to 436 MHz, analyzed 1.5 X 1014 spectral bins, and logged information on over 300 million signals. The fourth generation SERENDIP system expands on the SERENDIP III design. SERENDIP IV computes 200 billion operations each second providing spectral analysis on 168 million channels every 1.7 seconds. We will also discuss the design and use of the SERENDIP IV system and future observing plans.