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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2002

Broadband Direct Detection Submillimeter Spectrometer with Multiplexed Superconducting Transition Edge Thermometer Bolometers

We present performance results based on the first astronomical use of multiplexed superconducting bolometers as direct detectors (i.e., with cold electrons) for spectroscopy. The Fabry-Perot Interferometer Bolometer Research Experiment (FIBRE) is a broadband submillimeter spectrometer for the Caltech Submillimeter Observatory (CSO). FIBRE's detectors are superconducting transition edge sensor (TES) bolometers read out by a SQUID multiplexer. The Fabry-Perot uses a low resolution grating to order sort the incoming light. A linear bolometer array consisting of 16 elements detects this dispersed light, capturing 5 orders simultaneously from one position on the sky. With tuning of the Fabry-Perot over one free spectral range, a spectrum covering Delta lambda/lambda = 1/7 at a resolution of delta lambda/lambda = 1/1200 can be acquired. This spectral resolution is sufficient to resolve Doppler-broadened line emission from external galaxies. FIBRE has been operated in the 350 Am (850 GHz) band. These bands cover line emission from the important star formation tracers neutral carbon [CI] and carbon monoxide (CO).

Benford, D. J.↗
NASA NTRS2002

An Introduction to High-Energy Astrophysics: Detectors, Techniques and Missions

A series of lectures will be given to acquaint the amateur astronomer with historical, present and future methods of observation in high-energy astrophysics. These will begin with the basic principles of how photons of high energy are detected and their energy measured. The detectors and data distribution methods will be described. Finally, a comprehensive description of the experiments and missions in high-energy astrophysics will be reviewed.

Fishman, Gerald J.↗
NASA NTRS1982

Images of the future - Two decades in astronomy

Future instruments for the 100-10,000 A UV-wavelength region will require detectors with greater quantum efficiency, smaller picture elements, a greater wavelength range, and greater active area than those currently available. After assessing the development status and performance characteristics of vidicons, image tubes, electronographic cameras, digicons, silicon arrays and microchannel plate intensifiers presently employed by astronomical spacecraft, attention is given to such next-generation detectors as the Mosaicked Optical Self-scanned Array Imaging Camera, which consists of a photocathode deposited on the input side of a microchannel plate intensifier. The problems posed by the signal processing and data analysis requirements of the devices foreseen for the 21st century are noted.

Weistrop, D.↗
NASA NTRS1985

A cryogenically cooled, multidetector spectrometer for infrared astronomy

A liquid helium-cooled, 24 detector grating spectrometer was developed and used for low resolution astronomical observations in the 5 to 14 micron spectral range. The instrument operated on the 91 cm Kuiper Airborne Observatory, the 3 m IRTF (Mauna Kea), the 3 m Shane telescope (Lick Observatory), and the 152 cm NASA and University of Arizona telescope. The detectors are discrete Si:Bi photoconductors with individual metal oxide semiconductor field effect transistor preamplifiers operating at 4 K. The system uses a liquid helium-cooled slit, order-sorter filter, collimator mirror, grating, and camera mirror arranged in a Czerny-Turner configuration with a cold stop added between the collimator mirror and the grating. The distances between components are chosen so that the collimator mirror images the secondary mirror of the telescope onto the cold stop, thus providing a very effective baffle. Scattered radiation is effectively reduced by using liquid helium-cooled, black baffles to divide the spectrometer into three separate compartments. The system noise-equivalent flux density, when used on the 152 cm telescope from 8 to 13 microns with a resolving power of 50, is 4.4 x 10 to the minus 17th power W/sq cm micron square root of Hz. The main applications are for measuring continuum radiation levels and solid state emission and absorption features in regions of star and planet formation.

Witteborn, F. C.↗
NASA NTRS1984

Photometry with Multi-anode Microchannel Arrays (mamas) and Charge Injection Devices (cids)

The characteristics of two kinds of detectors are summarized with emphasis on those aspects that would affect their use in high accuracy astronomical photometry. The first type, the multianode microchannel arrays (MAMA), are a family of pulse counting array detectors. Components and operation principles are reviewed and quantum efficiency, noise characteristics, and dynamic range characteristics are described. The second type, charge injection devices (CID), are discussed in reference to their applicability to photometric detection at optical wavelengths.

Timothy, J. G.↗
NASA NTRS1986

Automated scanning of plastic nuclear track detectors using the Minnesota star scanner

The problems found in an attempt to adapt an automated scanner of astronomical plates, the Minnesota Automated Dual Plate Scanner (APS), to locating and measuring the etch pits produced by ionizing particles in plastic nuclear track detectors (CR-39) are described. A visual study of these pits was made to determine the errors introduced in determining positions and shapes. Measurements made under a low power microscope were compared with those from the APS.

Fink, P. J.↗
NASA NTRS1992

MOSAIC: Software for creating mosaics from collections of images

We have developed a powerful, versatile image processing and analysis software package called MOSAIC, designed specifically for the manipulation of digital astronomical image data obtained with (but not limited to) two-dimensional array detectors. The software package is implemented using the Interactive Data Language (IDL), and incorporates new methods for processing, calibration, analysis, and visualization of astronomical image data, stressing effective methods for the creation of mosaic images from collections of individual exposures, while at the same time preserving the photometric integrity of the original data. Since IDL is available on many computers, the MOSAIC software runs on most UNIX and VAX workstations with the X-Windows or Sun View graphics interface.

Varosi, F.↗
NASA NTRS1984

A cryogenically cooled, multidetector spectrometer for infrared astronomy

A liquid helium-cooled, 24 detector grating spectrometer was developed and used for low resolution astronomical observations in the 5 to 14 micron spectral range. The instrument operated on the 91 cm Kuiper Airborne Observatory, the 3 m IRTF (Mauna Kea), the 3 m Shane telescope Observatory, the 3 m Shane telescope (Lick Observatory), and the 152 cm NASA and University of Arizona telescope. The detectors are discrete Si:Bi photoconductors with individual metal oxide semiconductor field effect transistor preamplifiers operating at 4 K. The system uses a liquid helium-cooled slit, order-sorter filter, collimator mirror, grating, and camera mirror arranged in a Czerny-Turner configuration with a cold stop added between the collimator mirror and the grating. The distances between components are chosen so that the collimator mirror images the secondary mirror of the telescope onto the cold stop, thus providing a very effective baffle. Scattered radiation is effectively reduced by using liquid helium-cooled, black baffles to divide the spectrometer into three separate compartments. The system noise-equivalent flux density, when used on the 152 cm telescope from 8 to 13 microns with a resolving power of 50, is 4.4 x 10 to the minus 17th power W/sq cm micron square root of Hz. The main applications are for measuring continuum radiation levels and solid state emission and absorption features in regions of star and planet formation.

Witteborn, F. C.↗
NASA NTRS2008

Superconducting Films for Absorber-coupled MKID Detectors for Sub-millimeter and Far-infrared Astronomy

We describe measurements of the properties, at dc, gigahertz, and terahertz frequencies, of thin superconducting films with relatively high normal state sheet resistance. Such films can be applied to construct microwave kinetic inductance detector sensor arrays for submillimeter and far-infrared astronomical applications in which the incident power excites quasiparticles directly in a superconducting resonator that is configured to present a matched-impedance to the high frequency radiation being detected. For several materials, and a range of thicknesses down to 10 nm, we present measurements of normal state sheet resistance, resistance-temperature curves for the superconducting transition, quality factor and kinetic inductance fraction for microwave resonators made from patterned films, and terahertz measurements of the sheet impedance measured with a Fourier Transform Spectrometer.

Stevenson, T. R.↗
NASA NTRS1988

Apparent brightness of stars and lasers

Foremost among issues affecting the potential use of astrometric techniques to locate and track laser-carrying spacecraft is the apparent brightness of a laser relative to reference stars. Broadband detectors offer improved sensitivity to stars, but not to lasers. The important and fundamental step of calibrating laser and star brightnesses according to detector spectral sensitivity is performed for four representative kinds of broadband detectors, located above and below the atmosphere. Stars are identified according to parameters traditionally used by astronomers: temperature and apparent brightness at visible wavelengths. These are translated into an energy and photon flux for each kind of broadband detector and are then compared with the corresponding flux from a laser. The comparisons are also given as magnitude correction factors. Astrometrists typically characterize the sensitivity of their instruments in terms of the precision with which they can make a relative measurement of position and the minimum brightness needed to achieve that precision. Given this information and the instruments's spectral sensitivity, the calculations described can be used to infer the detectability of a laser and the precision with which it could be located and tracked. Since the limiting brightness quoted for a particular instrument is typically firm to within 4.0 dB, judging a laser's detectability by its visible brightness alone could lead to serious underestimation of the requirements on its effective radiated power. The laser brightness corrections given solve this problem.

Schumaker, B. L.↗
NASA NTRS2002

Low-Energy Study of Gamma-Ray Bursts Using Two BATSE Spectroscopy Detectors

Gamma-ray bursts (GRBs) are energetic, short-duration emissions of gamma-rays from astronomical sources typically well beyond our galaxy. The Burst and Transient Source Experiment (BATSE) that was onboard NASA's Compton Gamma-Ray Observatory (CGRO) had detected an unprecedented 2704 GRBs during CGRO's nine-year mission. BATSE consisted of eight detector assemblies located at the corners of CGRO to give full sky coverage. Each assembly consisted of two detectors, a Large Area Detector (LAD) and a Spectroscopy Detector (SD). In determining the detail features of GRBs, the degree to which they possess a low-energy component (approx. 10 keV) is of interest. Preece have developed a method to study the low-energy characteristics and concluded that 14% of the 86 bright GRBs they studied had a definite low-energy component, referred to as a low-energy excess. Their study, and for the present study as well, needed to use SD data, because it extends down to the low-energy range when operating in a high-gain mode. For their study, low-energy data was used from just one SD. To better quantify the low-energy behavior, this study will consider bursts for which two SDs satisfy the same criteria as used by Preece.

Michael J. Pangia↗
NASA NTRS1984

Algorithm for astronomical, extended source, signal-to-noise radio calculations

An algorithm was developed to simulate the expected signal-to-noise ratio as a function of observation time in the charge coupled device detector plane of an optical telescope located outside the Earth's atmosphere for an extended, uniform astronomical source embedded in a uniform cosmic background. By choosing the appropriate input values, the expected extended source signal-to-noise ratios can be computed for the Hubble Space Telescope using the Wide Field/Planetary Camera science instrument.

Jayroe, R. R.↗
NASA NTRS1979

A small helium-cooled infrared telescope for Spacelab 2

A helium cooled telescope of 15 cm aperture is being designed and constructed jointly by the University of Arizona, the Smithsonian Astrophysical Observatory and the Marshall Space Flight Center for high sensitivity infrared astronomical observations from Spacelab 2. A focal plane array of ten detectors provide a total field of view of 3 deg and cover the wavelength regions 4.5-8.5, 6-7, 9-16, 18-30 and 80-120 microns. A highly redundant all sky survey will be conducted by repeated scanning of the sky during many orbits of the spacecraft. High redundancy will allow discrimination among variable and constant celestial sources and several types of variable nearby sources. The principal astronomical result of the survey will be the absolute flux measurement of low surface brightness, large scale celestial infrared emissions but it will also extend existing IR sky surveys by a factor of 10 in point source sensitivity. The experiment will also make significant engineering measurements of contaminants in the Shuttle environment, test the technology of storage and utilization of large quantities of superfluid helium in space and test mechanical designs for future infrared telescopes for the Space Shuttle.

Gautier, T. N., III↗
NASA NTRS2002

Superconducting Bolometer Array Architectures

The next generation of far-infrared and submillimeter instruments require large arrays of detectors containing thousands of elements. These arrays will necessarily be multiplexed, and superconducting bolometer arrays are the most promising present prospect for these detectors. We discuss our current research into superconducting bolometer array technologies, which has recently resulted in the first multiplexed detections of submillimeter light and the first multiplexed astronomical observations. Prototype arrays containing 512 pixels are in production using the Pop-Up Detector (PUD) architecture, which can be extended easily to 1000 pixel arrays. Planar arrays of close-packed bolometers are being developed for the GBT (Green Bank Telescope) and for future space missions. For certain applications, such as a slewed far-infrared sky survey, feedhorncoupling of a large sparsely-filled array of bolometers is desirable, and is being developed using photolithographic feedhorn arrays. Individual detectors have achieved a Noise Equivalent Power (NEP) of -10(exp 17) W/square root of Hz at 300mK, but several orders of magnitude improvement are required and can be reached with existing technology. The testing of such ultralow-background detectors will prove difficult, as this requires optical loading of below IfW. Antenna-coupled bolometer designs have advantages for large format array designs at low powers due to their mode selectivity.

Benford, Dominic↗
NASA NTRS1970

Gamma-ray astronomy balloon results

Gamma ray astronomical point sources by balloon flight and satellite observation, discussing detector system and telescope for flux and energy spectrum

Fichtel, C. E.↗
NASA NTRS1973

Ultraviolet proximity focussed converters for use in a satellite SEC-TV system.

Performance characteristics of Bendix type BX08025-4522 proximity-focussed vacuum-ultraviolet to visible-light image converters are presented. The converters are to be used with SEC vidicons as detectors for an echelle spectrograph on the International Ultraviolet Explorer astronomical satellite. Magnesium fluoride input windows with Cs-Te photocathodes are used in the converters, with P-11 phosphors on the fiber optic output windows. Quantum efficiencies, modulation transfer function, background, geometric distortion, and environmental test results are presented for the wavelength region from 1150 to 3500 A.-

Feibelman, W. A.↗
NASA NTRS1974

Ultraviolet stellar spectrophotometry from a balloon platform

A 40 centimeter diameter aperture, balloon-borne telescope and ultraviolet spectrometer is described and selected scientific results are briefly reviewed. The general configuration of the 0.4 angstrom resolution instrument is shown and the utilization of servo-controlled secondary mirror, image dissector detector, and special mirror coatings are discussed. An outlook for astronomical research in the mid-ultraviolet from balloon-borne telescopes is presented together with future development plans for JSC's balloon-borne payload.

Kondo, Y.↗
NASA NTRS1993

Initial results from the extreme ultraviolet explorer

Data obtained during the first five months of calibration and science operation of the Extreme Ultraviolet Explorer (EUVE) are presented. Spectra of an extragalactic object were obtained; the object is detectable to wavelenghts longer than 100 A, demonstrating that extragalactic EUV astronomy is possible. Spectra of a hot white dwarf, and a late-type star in quiescence and flaring are shown as examples of the type of spectrographic data obtainable with EUVE. Other objects for which broad band photometric mode data have been obtained and analyzed include an RS CVn star and several late-type stars. The backgrounds in the EUVE detectors are quite low and the character of the diffuse astronomical EUV background has been investigated using these very low rates. Evidence is presented showing that, contrary to previously published reports, EUVE is about three times more sensitive than the English Wide Field Camera in the short wavelength bandpass covered by both instruments. Only limited information has been extracted from the longer bandpasses coered only by EUVE. Nonetheless, the brightest EUV source in the sky, a B star, has been discovered and is detected only in these longer bandpasses.

Bowyer, S.↗