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At least 559 records · Page 31

Galactic worms. I - Catalog of worm candidates

A catalog of candidates for the Galactic worms that are possibly the walls surrounding the superbubbles is compiled; 118 isolated structures that appear both in H I and in IR (60 and 100 microns). Fifty-two are possibly associated with H II regions. It is found that the 100-micron emissivity increases systematically toward the Galactic interior, which is consistent with the increase of the general interstellar radiation field. The 100-micron emissivity of the structures associated with the H II regions is larger than that of the structures without associated H II regions. The 60-100-micron ratio is large, 0.28 +/- 0.03, which may indicate that the grains associated with the atomic gas have a relatively large population of small grains. Thirty-five structures appear in the 408-MHz continuum. The IR and the radio continuum properties suggest that the 408-MHz continuum emission in those structures is very likely thermal. The implications of these results on the ionization of gas far from the Galactic plane are discussed.

Koo, Bon-Chul↗

Star trackers, star catalogs, and attitude determination - Probabilistic aspects of system design

Optimizing spacecraft attitude determination systems that use onboard star trackers requires analysis and evaluation of some probabilistic aspects of system design. This paper discusses methods of constructing or compiling optimum star catalogs, which are defined as uniform distributions on a sphere. Both local and global measures of uniformity on a sphere are defined. Application of these methods and measures to a specific problem is also discussed. In addition, Poisson models of star tracker acquisition probabilities are formulated to provide a useful analytical basis for designing and optimizing attitude determination systems. These analytical models and methods lead to rapid and realistic quantitative results, and should therefore facilitate making system performance trades. Use of such methods should also reduce the need for performing tedious computer simulations to obtain analogous results.

Vedder, John D.↗

The 1992 catalog of space science and applications education programs and activities

This catalog provides information on current, ongoing and pilot programs conducted at precollege through postdoctoral levels which are primarily funded or managed by the Office of Space Science Applications (OSSA). The directory of programs section includes teacher and faculty preparation and enhancement, student enrichment opportunities, student research opportunities, postdoctoral and advanced research opportunities, initiatives to strengthen educational institution involvement in research and initiatives to strengthen research community involvement in education. The Educational Products appendices include tabular data of OSSA activities, NASA Spacelink, NASA education satellites videoconferences, the Teacher Resource Center Network, and a form for requesting further information.

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Electronic Catalog Of Extragalactic Objects

NASA/IPAC Extragalactic Database (NED) is publicly accessible computerized catalog of published information about extragalactic observations. Developed to accommodate increasingly large sets of data from surveys, exponentially growing literature, and trend among astronomers to take multispectral approach to astrophysical problems. Accessible to researchers and librarians.

Helou, George↗

NASA scientific and technical publications: A catalog of special publications, reference publications, conference publications, and technical papers, 1991-1992

This catalog lists 458 citations of all NASA Special Publications, NASA Reference Publications, NASA Conference Publications, and NASA Technical Papers that were entered into the NASA Scientific and Technical Information database during accession year 1991 through 1992. The entries are grouped by subject category. Indexes of subject terms, personal authors, and NASA report numbers are provided.

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Space Station Freedom biomedical monitoring and countermeasures: Biomedical facility hardware catalog

This hardware catalog covers that hardware proposed under the Biomedical Monitoring and Countermeasures Development Program supported by the Johnson Space Center. The hardware items are listed separately by item, and are in alphabetical order. Each hardware item specification consists of four pages. The first page describes background information with an illustration, definition and a history/design status. The second page identifies the general specifications, performance, rack interface requirements, problems, issues, concerns, physical description, and functional description. The level of hardware design reliability is also identified under the maintainability and reliability category. The third page specifies the mechanical design guidelines and assumptions. Described are the material types and weights, modules, and construction methods. Also described is an estimation of percentage of construction which utilizes a particular method, and the percentage of required new mechanical design is documented. The fourth page analyzes the electronics, the scope of design effort, and the software requirements. Electronics are described by percentages of component types and new design. The design effort, as well as, the software requirements are identified and categorized.

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Using machine learning techniques to automate sky survey catalog generation

We describe the application of machine classification techniques to the development of an automated tool for the reduction of a large scientific data set. The 2nd Palomar Observatory Sky Survey provides comprehensive photographic coverage of the northern celestial hemisphere. The photographic plates are being digitized into images containing on the order of 10(exp 7) galaxies and 10(exp 8) stars. Since the size of this data set precludes manual analysis and classification of objects, our approach is to develop a software system which integrates independently developed techniques for image processing and data classification. Image processing routines are applied to identify and measure features of sky objects. Selected features are used to determine the classification of each object. GID3* and O-BTree, two inductive learning techniques, are used to automatically learn classification decision trees from examples. We describe the techniques used, the details of our specific application, and the initial encouraging results which indicate that our approach is well-suited to the problem. The benefits of the approach are increased data reduction throughput, consistency of classification, and the automated derivation of classification rules that will form an objective, examinable basis for classifying sky objects. Furthermore, astronomers will be freed from the tedium of an intensely visual task to pursue more challenging analysis and interpretation problems given automatically cataloged data.

Fayyad, Usama M.↗

A catalog of intracluster gas temperatures

We have searched the Einstein Monitor Proportional Counter (MPC) data base for observations of clusters of galaxies. By coadding the MPC spectra obtained during all pointed observations of clusters with IPC count rates greater than 0.1 counts/s, we have obtained sufficient photon statistics to estimate the X-ray temperature of 84 clusters. Combining the MPC results with EXOSAT and Ginga results reported in the literature yields a combined sample of 104 clusters with known X-ray temperatures. One of the best studied X-ray correlations between clusters is that between their X-ray luminosity and gas temperature. We show that the best-fit power-law relation for our combined cluster sample can be explained by the observed increase in the gas-to-stellar mass ratio between low- and high-temperature clusters. The statistical significance of any evolution in our combined X-ray sample has been examined and compared with the statistical properties of clusters culled from optical catalogs. We find that there is strong evidence for a decrease in the X-ray luminosity of optically rich clusters beyond z approximately about 0.06. This result is used to estimate the normalization of the primordial power spectrum of density fluctuations.

David, L. P.↗

Ultraviolet Spectrometer and Polarimeter (UVSP) catalog of observations. Volume 3: Experiments 63058-99771 (February 1988 - November 1989)

A catalog of a observations (experiments) obtained by the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission (SMM) from Nov. 1980 to Nov. 1989 is provided. The information for each entry includes the time of each observation, the observed position of the Sun, the spacecraft roll angle, the slit used, and instrument parameters such as raster size, pixel spacing, wavelength, polarimeter usage, gate time, etc. The document is split into three volumes: Volume 1 contains experiments 1-30719 (Feb. 1980 - Apr. 1985); Volume 2 contains experiments 30720-63057 (Apr. 1985 - Feb. 1988); and Volume 3 contains experiments 63058-99771 (Feb. 1988 - Nov. 1989).

Henze, William, Jr.↗

Ultraviolet spectrometer and polarimeter (UVSP) catalog of observations. Volume 1: Experiments 1-30719, February 1980 - April 1985

A catalog of observations (experiments) obtained by the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission (SMM) from Feb. 1980 to Nov. 1989 is presented. The information for each entry includes the time of each observation, the observed position of the Sun, the spacecraft roll angle, the slit used, and instrument parameters such as raster size, pixel spacing, wavelength, polarimeter usage, gate time, etc. The document is split into three volumes: Volume 1 contains experiments 1-30719 (February 1980-April 1985); Volume 2 contains experiments 30720-63057 (April 1985-February 1988); and Volume 3 contains experiments 63058-99771 (February l988-November 1989).

Henze, William, Jr.↗

Ultraviolet spectrometer and polarimeter (UVSP) catalog of observations. Volume 2: Experiments 30720-63057, April 1985 - February 1988

A catalog of observations (experiments) obtained by the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission (SMM) from Feb. 1980 to Nov. 1989 is presented. The information for each entry includes the time of each observation, the observed position of the Sun, the spacecraft roll angle, the slit used, and instrument parameters such as raster size, pixel spacing, wavelength, polarimeter usage, gate time, etc. The document is split into three volumes: Volume 1 contains experiments 1-30719 (February 1980-April 1985); Volume 2 contains experiments 30720-63057 (April 1985-February 1988); and Volume 3 contains experiments 63058-99771 (February 1988-November 1989).

Henze, William, Jr.↗

Catalog of Apollo experiment operations

This catalog reviews Apollo mission reports, preliminary science reports, technical crew debriefings, lunar surface operations plans, and various relevant lunar experiment documents, collecting engineering- and operation-specific information by experiment. It is organized by discrete experimental and equipment items emplaced or operated on the lunar surface or at zero gravity during the Apollo missions. It also attempts to summarize some of the general problems encountered on the surface and provides guidelines for the design of future lunar surface experiments with an eye toward operations. Many of the problems dealt with on the lunar surface originated from just a few novel conditions that manifested themselves in various nasty ways. Low gravity caused cables to stick up and get caught on feet, and also made it easy for instruments to tip over. Dust was a problem and caused abrasion, visibility, and thermal control difficulties. Operating in a pressure suit limited a person's activity, especially in the hands. I hope to capture with this document some of the lessons learned from the Apollo era to make the jobs of future astronauts, principle investigators, engineers, and operators of lunar experiments more productive.

Sullivan, Thomas A.↗

Activity Catalog Tool (ACT) user manual, version 2.0

This report comprises the user manual for version 2.0 of the Activity Catalog Tool (ACT) software program, developed by Leon D. Segal and Anthony D. Andre in cooperation with NASA Ames Aerospace Human Factors Research Division, FLR branch. ACT is a software tool for recording and analyzing sequences of activity over time that runs on the Macintosh platform. It was designed as an aid for professionals who are interested in observing and understanding human behavior in field settings, or from video or audio recordings of the same. Specifically, the program is aimed at two primary areas of interest: human-machine interactions and interactions between humans. The program provides a means by which an observer can record an observed sequence of events, logging such parameters as frequency and duration of particular events. The program goes further by providing the user with a quantified description of the observed sequence, through application of a basic set of statistical routines, and enables merging and appending of several files and more extensive analysis of the resultant data.

Segal, Leon D.↗

Applications catalog of pyrotechnically actuated devices/systems

A compilation of basic information on pyrotechnically actuated devices/systems used in NASA aerospace and aeronautic applications was formatted into a catalog. The intent is to provide (1) a quick reference digest of the types of operational pyro mechanisms and (2) a source of contacts for further details. Data on these items was furnished by the NASA Centers that developed and/or utilized such devices to perform specific functions on spacecraft, launch vehicles, aircraft, and ground support equipment. Information entries include an item title, user center name, commercial contractor/vendor, identifying part number(s), a basic figure, briefly described purpose and operation, previous usage, and operational limits/requirements.

Seeholzer, Thomas L.↗

Spectroscopic CCD surveys for quasars at large redshift. 3: The Palomar Transit Grism Survey catalog

This paper reports the initial results of the Palomar Transit Grism Survey (PTGS). The PTGS was designed to produce a sample of z greater than 2.7 quasars that were identified by well-defined selection criteria. The survey consists of six narrow (approximately equal to 8.5 min wide) strips of sky; the total effective area is 61.47 sq deg. Low-resolution slitless spectra, covering the wavelength range from 4400 to 7500 A, were obtained for approximately 600 000 objects. The wavelength- and flux-calibrated spectra were searched for emission lines with an automatic software algorithm. A total to 1655 emission features in the grism data satisfied our signal-to-noise ratio and equivalent width selection criteria; subsequent slit spectroscopy of the candidates confirmed the existence of 1052 lines (928 different objects). Six groups of emission lines were detected in the survey: Lyman alpha + N V, C IV, C III1, Mg II, H Beta + (O III), and H alpha + (S II). More than two-thirds of the candidates are low-redshift (z less than 0.45) emission-line galaxies; ninety objects are high-redshift quasars (z greater than 2.7) detected via their Lyman alpha + N V emission lines. The survey contains three previously unknown quasars brighter than 17th magnitude; all three have redshifts of approximately equal to 1.3. In this paper we present the observational properties of the survey, the algorithms used to select the emission-line candidates, and the catalog of emission-line objects.

Schneider, Donald P.↗

The Guide Star Catalog and related sky surveys

The basic properties and foundations of the Guide Star Catalog (GSC) are presented. Special emphasis is given to the published versions of the GSC, and the project on image compression and distribution of the digitized survey plate scans is mentioned.

Jenkner, Helmut↗