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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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At least 397 records · Page 22

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NASA NTRS1979

X-ray emitting BL Lacertae objects located by the scanning modulation collimator experiment on HEAO 1

It is established that BL Lacertae objects constitute a class of X-ray emitter by precisely locating X-ray sources identified with Mrk 421, PKS 0548-322, PKS 2155-304, and 2A 1219+305. Irregular variations of the order of 1 mag, characteristic of BL Lacertae objects, are reported for the last two objects. The measurement of an extremely steep X-ray spectrum from Mrk 421, in contrast to previous flat X-ray spectra above 3 keV, suggests that different structural states of an accretion disk are being observed.

Schwartz, D. A.↗

NASA NTRS1979

Near infrared photographic sky survey. 1: Catalog of red stellar objects

Red stellar objects for which V-1 was greater than a value of about 2 (supm). 5 were extracted from photographs of 23 program fields. Tabular data for each field show the object name; the 1950 epoch right ascension, declination, galactic longitude, galactic latitude; radial distance from field venter in decimal degrees; color classes; and objects ordered by redness.

Craine, E. R.↗

NASA NTRS1979

Procedure for the formation of a coating on an object by polymerization by luminescent discharge

The object to be coated was placed in a reaction area located in a luminescent discharge chamber. By introducing the polymerizable material in this reaction area and applying an electrical field to this reaction, a polymerized film was obtained on the coating object under controlled conditions. By the use of thermomechanical treatment on the object, the undesirable effects of discoloration, brittleness, and viscosity can be controlled.

Source record↗

NASA NTRS1980

Objective measurement of human tolerance to +G sub z acceleration stress

The efficacy of a new objective technique using a transcutaneous Doppler flowmeter to monitor superficial temporal artery blood flow velocity during acceleration was investigated. The results were correlated with current objective and subjective G tolerance end points. In over 1300 centrifuge runs, retrograde eye level blood flow leading to total flow cessation was consistently recorded and preceded visual field deterioration leading to blackout by 3 to 23 seconds. The new method was successfully applied as an objective indication of tolerance in a variety of test situations including evaluation of g-suits, straining maneuvers, and 13 deg, 45 deg and 65 deg set back angles.

Rositano, S. A.↗

NASA NTRS1979

Investigation of small solar system objects with the space telescope

The application of the space telescope (ST) to study small objects in the solar system in order to understand the birth and the early evolution of the solar system is discussed. The upper size limit of the small bodies is defined as approximately 5000 km and includes planetary satellites, planetary rings, asteroids, and comets.The use of the astronomical instruments aboard the ST, such as the faint object camera, ultraviolet and infrared spectrometers, and spectrophotometers, to study the small solar system objects is discussed.

Morrison, D.↗

NASA NTRS1980

Variable X-ray spectra of BL Lac objects: HEAO-1 observations of PKS 0548-322 and 2A 1219+305

X-ray spectra for the BL Lac objects PKS 0548-322 and 2A 1219+305 measured with the HEAO-1 A2 detectors during pointing maneuvers on September 30, 1978 and May 31, 1978 respectively are presented. Both fit single power law components with low energy absorption. For 2A 1219+305, a thermal bremsstrahlung form gives an unacceptable fit. From a comparison with other statistically poorer observations taken at 6 month intervals while the satellite was in its normal scanning mode, it is found that the sources exhibit spectral variability. A summary of measurements of the 5 BL Lac objects detected with the A2 experiment is presented and it is concluded that X-ray spectral changes in this class of source are common. Their general X-ray spectral characteristics distinguish BL Lac objects from other classes of X-ray emitting active galactic nuclei. Analysis of their total spectra indicates that most of the energy is emitted in the 5 to 100 eV band.

Worrall, D. M.↗

NASA NTRS1979

Faint-object spectrograph for Space Telescope

The paper presents the Faint Object Spectrograph (FOS) for the Space Telescope to provide a digitized spectra of faint astronomical objects over the 115 to 700 nm wavelength range at resolving powers of 1000 and 100. A variety of concave gratings and prisms is employed to form nearly stigmatic spectra on one of the two Digicon photon counting detectors which are optimized for two different but overlapping ranges. The scientific goals associated with quasars, active galaxies, and objects within our solar system are discussed, and the FOS optical design features, including detectors, electronics, signal processing, power supplies, and data handling are examined. The FOS structural system, mechanism, and controls are described, along with the predicted performance capabilities in the spectral and spectropolarimetry modes. Finally, system performance parameters, including spatial resolution, time resolution, noise, and efficiency are discussed.

Harms, r. J.↗

NASA NTRS1979

Object migration and authentication

The paper presents a mechanism permitting a type manager to fabricate a migrated object representation which can be entrusted to other subsystems or transmitted outside of the control of a local computer system. The migrated object representation is signed by the type manager in such a way that the type manager's signature cannot be forged and the manager is able to authenticate its own signature. Subsequently, the type manager can retrieve the migrated representation and validate its contents before reconstructing the object in its original representation. This facility allows type managers to authenticate the contents of off-line or network storage and solves problems stemming from the hierarchical structure of the system itself.

Gligor, V. D.↗

NASA NTRS1979

Optical and X-ray properties of the newly discovered BL Lacertae object PKS 2155-304 /= H2155-304/

The soft X-ray source H 2155-304 has been precisely located with the HEAO 1 scanning modulation collimator, and identified with an object of bolometric magnitude approximately 14. The linear polarization, variability, spectrum, and diffuse image of the optical flux, together with the positional coincidence of the radio source PKS 2155-304, indicate that this object is a new member of the BL Lacertae class. Its characteristics are compared with those of other X-ray-emitting BL Lacertae objects, particularly Mrk 421.

Griffiths, R. E.↗

NASA NTRS1980

Red and nebulous objects in dark clouds - A survey

A search on the NGS-PO Sky Survey photographs has revealed 150 interesting nebulous and/or red objects, mostly lying in dark clouds and not previously catalogued. Spectral classifications are presented for 55 objects. These indicate a small number of new members of the class of Herbig-Haro objects, a significant number of new T Tauri stars, and a few emission-line hot stars. It is argued that hot, high-mass stars form preferentially in the dense cores of dark clouds. The possible symbiosis of high and low mass stars is considered. A new morphology class is defined for cometary nebulae, in which a star lies on the periphery of a nebulous ring.

Cohen, M.↗

NASA NTRS1980

System for forming a quadrified image comprising angularly related fields of view of a three dimensional object

A system for generating, within a single frame of photographic film, a quadrified image including images of angularly (including orthogonally) related fields of view of a near field three dimensional object is described. It is characterized by three subsystems each of which includes a plurality of reflective surfaces for imaging a different field of view of the object at a different quadrant of the quadrified image. All of the subsystems have identical path lengths to the object photographed.

Chamberlain, F. R.↗

NASA NTRS1981

Objective analysis of observational data from the FGGE observing systems

An objective analysis procedure for updating the GLAS second and fourth order general atmospheric circulation models using observational data from the first GARP global experiment is described. The objective analysis procedure is based on a successive corrections method and the model is updated in a data assimilation cycle. Preparation of the observational data for analysis and the objective analysis scheme are described. The organization of the program and description of the required data sets are presented. The program logic and detailed descriptions of each subroutine are given.

Baker, W.↗

NASA NTRS1981

An objective isobaric/isentropic technique for upper air analysis

An objective meteorological analysis technique is presented whereby both horizontal and vertical upper air analyses are performed. The process used to interpolate grid-point values from the upper-air station data is the same as for grid points on both an isobaric surface and a vertical cross-sectional plane. The nearby data surrounding each grid point are used in the interpolation by means of an anisotropic weighting scheme, which is described. The interpolation for a grid-point potential temperature is performed isobarically; whereas wind, mixing-ratio, and pressure height values are interpolated from data that lie on the isentropic surface that passes through the grid point. Two versions (A and B) of the technique are evaluated by qualitatively comparing computer analyses with subjective handdrawn analyses. The objective products of version A generally have fair correspondence with the subjective analyses and with the station data, and depicted the structure of the upper fronts, tropopauses, and jet streams fairly well. The version B objective products correspond more closely to the subjective analyses, and show the same strong gradients across the upper front with only minor smoothing.

Mancuso, R. L.↗

NASA NTRS1980

Pareto-optimal multi-objective design of airplane control systems

A constrained minimization algorithm for the computer aided design of airplane control systems to meet many requirements over a set of flight conditions is generalized using the concept of Pareto-optimization. The new algorithm yields solutions on the boundary of the achievable domain in objective space in a single run, whereas the older method required a sequence of runs to approximate such a limiting solution. However, Pareto-optimality does not guarantee a satisfactory design, since such solutions may emphasize some objectives at the expense of others. The designer must still interact with the program to obtain a well-balanced set of objectives. Using the example of a fighter lateral stability augmentation system (SAS) design over five flight conditions, several effective techniques are developed for obtaining well-balanced Pareto-optimal solutions. For comparison, one of these techniques is also used in a recently developed algorithm of Kreisselmeier and Steinhauser, which replaces the hard constraints with soft constraints, using a special penalty function. It is shown that comparable results can be obtained.

Schy, A. A.↗

NASA NTRS1981

Extremely red compact radio sources - The empty field objects

Radiation of 10 microns has been detected from 1413+135, one of the very red objects discovered by Rieke, Lebofsky, and Kinman (1979) at near-infrared wavelengths. The spectrum of this object flattens at wavelengths longer than 2.2 microns. Upper limits are also given for the 10-micron emission from 2255+14, 0026+34, and 0406+121. Photometry between 1.25 and 2.2 microns confirms the variability of 1413+135, 2255+41, and 0406+121. Five percent resolution spectra of 1413+135 and 0406+121 between 1.5 and 2.4 microns show no emission or absorption lines. The spectral data rule out the possibility that 1413+135 is a quasar with normal line strengths and a redshift less than 1.3 and greater than 4. The lack of features of the 1.5-2.4-micron spectra, the rapid variability, and the overall shape of the radio, infrared, and X-ray energy distributions are consistent with a BL Lac nature for these objects.

Beichman, C. A.↗

NASA NTRS1981

Holographic interferometry of transparent media with reflection from imbedded test objects

In applying holographic interferometry, opaque objects blocking a portion of the optical beam used to form the interferogram give rise to incomplete data for standard computer tomography algorithms. An experimental technique for circumventing the problem of data blocked by opaque objects is presented. The missing data are completed by forming an interferogram using light backscattered from the opaque object, which is assumed to be diffuse. The problem of fringe localization is considered.

Prikryl, I.↗

NASA NTRS1981

Compact objects

Various types of objects and phenomena and their significance in high energy astrophysics are discussed. The current concepts of the nature of the objects and the mechanisms generating high energy electromagnetic radiation are also discussed. Current observational data is presented. Objects of special interest include black holes, supernova remnants, neutron stars, and pulsars.

Source record↗

NASA NTRS1982

Simultaneous multifrequency observations of BL Lac objects and violently variable quasars

Ultraviolet spectra simultaneous with radio, infrared, optical, and X-ray measurements were obtained for three BL Lac objects and one violently variable quasar during several epochs (0735+178, BL Lac, IZw-187, and 3C446). A feature common to these objects is that the radio-mm continuum must steepen in the far-infrared region in order to connect smoothly to the IR-UV continuum. This indicates that synchrotron emission becomes optically thick in the mm or far-infrared region. The continuum of 3C446 and BL Lac steepen quite rapidly between the IR and UV spectra with slopes near unity. The X-ray emission in BL Lac, 3C446, and 0735+178 has a different origin from the IR-UV radiation, probably from the inverse Compton process. However, the synchrotron radiation is the probable source of X-ray emission in the X-ray bright BL Lac object IZw-187. In IZw-187, most of the energy emerges in the UV - X-ray region, while for the other sources, most of the energy emerges in the far infrared region.

Bregman, J. N.↗