Optical Identification and Clustering Properties of Non-Cluster, Moderate-Power Radio Sources
Explore the source record for details and available documents.
Optical Identification Clustering Properties↗
SEARCH · Search NASA
Results for “source identification”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Hydrologic Baseline Conditions and Projected Trends for Kennedy Space Center and the Cape Canaveral Barrier Island Complex
The purpose of this document is the creation of a comprehensive collection of data, information and knowledge on the eco-hydrologic setting, and current and predicted (2030 -2080) hydrologic conditions that will directly and indirectly influence the Kennedy Space Center (KSC) industrial and ecological system. Focus is on identification of existing data sources (web based, published, in-house) and identification of future possible needs. The document will aid in assessment of risks to the National Aeronautics and Space Administration (NASA) and stakeholder missions associated with changing local, regional and global conditions. This living document will allow for rapid updates as new data and improved spatial data (LiDAR elevations, land use, land cover, runoff coefficients, etc.) are accumulated by the Environmental Management Branch (EMB), stakeholders, and supporting staff from the NASA Environmental and Medical Contract (NEMCON) currently managed by Herndon Solutions Group LLC. (HSG).The report summarizes and visualizes hydrologic conditions supporting long-term trends monitoring, management and regulatory compliance needs, climate risk mitigation, and achievement of KSC and stakeholder’s sustainability goals. Future utility may extend to implementation actions of the KSC future development plan, KSC updates to future KSC Environmental Resource Documents (ERD), and the regional multi-agency Indian River Lagoon Health Initiative.
Carlton Hall↗
Development of a Microphone Phased Array Capability for the Langley 14- by 22-Foot Subsonic Tunnel
A new aeroacoustic measurement capability has been developed for use in open-jet testing in the NASA Langley 14- by 22-Foot Subsonic Tunnel (14x22 tunnel). A suite of instruments has been developed to characterize noise source strengths, locations, and directivity for both semi-span and full-span test articles in the facility. The primary instrument of the suite is a fully traversable microphone phased array for identification of noise source locations and strengths on models. The array can be mounted in the ceiling or on either side of the facility test section to accommodate various test article configurations. Complementing the phased array is an ensemble of streamwise traversing microphones that can be placed around the test section at defined locations to conduct noise source directivity studies along both flyover and sideline axes. A customized data acquisition system has been developed for the instrumentation suite that allows for command and control of all aspects of the array and microphone hardware, and is coupled with a comprehensive data reduction system to generate information in near real time. This information includes such items as time histories and spectral data for individual microphones and groups of microphones, contour presentations of noise source locations and strengths, and hemispherical directivity data. The data acquisition system integrates with the 14x22 tunnel data system to allow real time capture of facility parameters during acquisition of microphone data. The design of the phased array system has been vetted via a theoretical performance analysis based on conventional monopole beamforming and DAMAS deconvolution. The performance analysis provides the ability to compute figures of merit for the array as well as characterize factors such as beamwidths, sidelobe levels, and source discrimination for the types of noise sources anticipated in the 14x22 tunnel. The full paper will summarize in detail the design of the instrumentation suite, the construction of the hardware system, and the results of the performance analysis. Although the instrumentation suite is designed to characterize noise for a variety of test articles in the 14x22 tunnel, this paper will concentrate on description of the instruments for two specific test campaigns in the facility, namely a full-span NASA Hybrid Wing Body (HWB) model entry and a semi-span Gulfstream aircraft model entry, tested in the facility in the winter of 2012 and spring of 2013, respectively.
Humphreys, William M.↗
A Case Study in RFI at L-band Detected by SMAP
Even when radio frequency interference (RFI) is detected, very little is known about the sources of the interference. More information about the sources would facilitate the design of systems to deal with the interference. Reporting of interference by the RFI teams for SMAP and SMOS through international channels has resulted in a decrease in RFI and identification of several sources. Two such cases that have been identified in the USA and are reported here.
Radiometry↗
Einstein observations of the Orion Nebula
A single 3.5 hour observation on 1979 March 6 with the imaging proportional counter aboard the Einstein Observatory has revealed the presence of numerous low-luminosity (10 to the 31st ergs/s) X-ray sources in a region centered near the Trapezium in the Orion Nebula. In addition to the Trapezium, 22 discrete sources have been detected in a 1 x 1 deg field at or above the 4 sigma level. These sources are clearly associated with star formation, as indicated by the similarity of their spatial distribution with that of the nebular variables, a class of pre-main-sequence stars. Because the field is quite crowded, however, individual identifications of these sources are difficult. In addition to the discrete sources, there is evidence for diffuse or unresolved emission from two ridges extending 16 deg to the north and 15 deg to the west of the Trapezium. The nature of the discrete sources and of the diffuse emission is discussed.
Ku, W. H.-M.↗
Sources, losses, and transport of magnetospherically trapped particles.
Trapping, pseudo-trapping, and non-trapping regions within an observed magnetospheric configuration are described. Time averaged proton and electron distributions and available data concerning the alpha particle distribution within the trapping and pseudo-trapping regions are presented. A review of the observational evidence leading to the identification of major sources, losses, and transport of magnetospherically trapped particles is given. Conclusions are summarized and additional suggestions offered on these factors for inner and outer zone protons and electrons. One general result of this review is that much is now known of source, loss, and transport processes, although specific experiments and calculations must still be done. It is shown that the inclusion of pitch angle diffusion processes within the magnetosphere significantly alters the concept of stable trapping and allows a consistent quiescent description of outer zone electrons to be formulated from energies of a few tens of kilovolts to several MeV.
Williams, D. J.↗
Search for an X-ray identification of a strong gamma-ray source
X-rays from Cygnus X-3 were observed during early 1978 with the detectors of the SAS-3 satellite. These observations in conjunction with earlier UHURU and ANS data indicate that the 4.8 hr period of Cygnus X-3 is increasing at the rate of P/P = (5/1 plus or minus 1.3) x 10 to the minus 6 power/1 yr. The sign and magnitude for this change are incompatible with a rotation model for the period and are in reasonable agreement with model predictions for orbital changes associated with mass loss and transfer in a binary system.
Lamb, R. C.↗
Identification of the variable X-ray sources GX 339-4 and MXB 1659-29 by the scanning modulation collimator on HEAO 1
Explore the source record for details and available documents.
Doxsey, R.↗
Identification of a faint X-ray source with the W Ursae Majoris star VW Cephei
The NRL instrument aboard the HEAO 1 satellite has detected a faint X-ray source, which has been identified tentatively with the contact binary star (W UMa variable) VW Cephei. Its luminosity is between 3 x 10 to the 30th and 4 x 10 to the 31st ergs/sec (0.1-10 keV), and the results suggest some variation of the X-ray flux with phase.
Carroll, R. W.↗
Identification of Optical Component of North Toroidal Source of Sporadic Meteors and its Origin
We succeeded to identify the North Toroidal source by optical observations performed by the SonotaCo Network, which is a TV observation network coordinated by Japanese amateurs. This source has been known only for radar observations until now. The orbits of the optical meteors in the North Toroidal source are relatively large eccentricity and semi-major axis, compared with those of the radar meteors. In this paper, we report the characteristics of this North Toroidal source detected by optical observations, and discuss the possible origin and evolution of this source.
Hashimoto, T.↗
Photoabsorption and photodissociation of molecules important in the interstellar medium
Photoabsorption and fluorescence cross sections of molecules important in the interstellar medium were measured in the 90 to 200 nm region using synchrotron radiation, excimer laser, and condensed discharge lamps as light sources. The quantitative spectroscopic data are currently needed for the modeling of formation and destruction rates of molecules by the interstellar radiation field. Fluorescences from excited photofragments produced by vacuum ultraviolet radiation of molecules are dispersed to identify the emitting species. The fluorescence data are useful for the identification of emission sources in interstellar clouds.
Lee, Long C.↗
An X-ray and radio study of steep-spectrum radio sources. II - Four fields from a 22 MHz polar cap survey
Four fields containing radio sources with spectral indices greater than unity at low frequencies have been observed over a wide range of radio wavelengths and at X-ray wavelengths. For most of the steep-spectrum sources no optical identifications have been found to the detection limit of the Palomar Schmidt prints, even with the positional precision of about 1 arcsec from VLA maps. This implies that the associated galaxies or clusters lie at a great distance. X-ray emission was not detected from any of the steep-spectrum radio sources. In one case, an extended source appears to be a radio halo in an uncataloged cluster of galaxies at a redshift of 0.125, and it is suggested that this object is a promising candidate for the detection of inverse Compton X-rays, since it is not a high-luminosity source of thermal X-rays.
Dewdney, P. E.↗
External Contamination Control of Attached Payloads on the International Space Station
The International Space Station (ISS) is an on-orbit platform for science utilization in low Earth orbit with multiple sites for external payloads with exposure to the natural and induced environments. Contamination is one of the induced environments that can impact performance, mission success and science utilization on the vehicle. This paper describes the external contamination control requirements and integration process for externally mounted payloads on the ISS. The external contamination control requirements are summarized and a description of the integration and verification process is detailed to guide payload developers in the certification process of attached payloads on the vehicle. A description of the required data certification deliverables covers the characterization of contamination sources. Such characterization includes identification, usage and operational data for each class of contamination source. Classes of external contamination sources covered are vacuum exposed materials, sources of leakage, vacuum venting and thrusters. ISS system level analyses are conducted by the ISS Space Environments Team to certify compliance with external contamination control requirements. This paper also addresses the ISS induced contamination environment at attached payload sites, both at the requirements level as well as measurements made on ISS.
Soares, Carlos E.↗
MX 1313+29 - A compact source of very low energy X-rays in Coma Berenices
A compact X-ray source near the North Galactic Pole has been detected with the low-energy X-ray telescope aboard the SAS-3 satellite. The spectral temperature of the source is less than 1 million K, and the energy flux at the earth is 3 by 10 to the -10th power erg/sq cm/sec above 0.1 keV. The flux appeared to be constant both on short time scales (10-1000 s), and over the interval from the first SAS-3 observation (June 12, 1975) to the latest (July 15, 1975). The possible identification of this source with the hot white dwarf HZ 43 is discussed.
Hearn, D. R.↗
Near earth magnetic disturbance in total field at high latitudes. 2: Interpretation of data from OGO's 2, 4, and 6
Variations in the scalar magnetic field (delta B) from the polar orbiting OGO 2, 4, and 6 spacecraft, with supporting vector magnetic field data from surface observatories, were analyzed at dipole latitudes above 55 deg. Although individual satellite passes, at low altitudes, confirm the existence of electrojet currents, neither individual satellite passes nor contours of average delta B are consistent with latitudinally narrow electrojet currents as the principal source of delta B at the satellite. The ratio of delta B magnitudes in positive and negative regions is variable. The characteristics of the negative delta B region indicate a latitudinally broad ionospheric source. Comparison of the surface magnetic disturbance caused by the equivalent current with the measured average surface disturbance shows good agreement except in localized details. Because delta B decreases very slowly with altitude in the positive delta B region, it is not possible to account for this disturbance in terms of ionospheric currents. The contribution to the satellite delta B due to a model electrojet, which reproduced the measured average surface horizontal disturbance, was computed. Definitive identification of all sources of positive delta B is not possible at this time.
Langel, R. A.↗
Graph-based real-time fault diagnostics
A real-time fault detection and diagnosis capability is absolutely crucial in the design of large-scale space systems. Some of the existing AI-based fault diagnostic techniques like expert systems and qualitative modelling are frequently ill-suited for this purpose. Expert systems are often inadequately structured, difficult to validate and suffer from knowledge acquisition bottlenecks. Qualitative modelling techniques sometimes generate a large number of failure source alternatives, thus hampering speedy diagnosis. In this paper we present a graph-based technique which is well suited for real-time fault diagnosis, structured knowledge representation and acquisition and testing and validation. A Hierarchical Fault Model of the system to be diagnosed is developed. At each level of hierarchy, there exist fault propagation digraphs denoting causal relations between failure modes of subsystems. The edges of such a digraph are weighted with fault propagation time intervals. Efficient and restartable graph algorithms are used for on-line speedy identification of failure source components.
Padalkar, S.↗
High-precision infrared sky survey at wavelength 2.7 microns
Preliminary results of an infrared survey of the equatorial sky zone (declinations 10 S to 10 N) with U.S. Air Force satellite sensors show that positions of previously unknown infrared sources are measured with an rms accuracy of 4 arc seconds, which is six times better than the best previous infrared survey. The search area per source for further study is thus 36 times smaller, so that identification of the infrared sources with optical objects in catalogs and sky photographs is facilitated, as is reacquisition of the sources with ground-based infrared telescopes. The survey extends the content of near-infrared source catalogs to lower flux densities and adds information at a wavelength not observable from the ground. Objects found in the survey include cool giants and supergiants, long-period and semi-regular variable stars, and sources identified with faint red stars visible on the Palomar Observatory Sky Survey.
Sweeney, L. H.↗
RE J1255+266: Detection of an extremely bright EUV transient
During a pointed ROSAT observation in the direction of the Coma cluster of galaxies an exceptionally bright EUV source, RE J1255+266, was detected serendipitously. The source is located close to the Galactic North Pole, at b(sub II) is approximately or equal to 89 deg. Its observed EUV flux (62 - 110 eV) at the time of the detection was of order 7 x 10(exp -9) ergs/sq cm, making RE J1255+266 temporarily one of the brightest EUV sources on the sky. The EUV flare of RE J1255+266 has a light curve with a decay time of about 0.86 days. With respect to earlier non-detections, the source brightened by a factor of approximately 7000. Such a behavior has not been observed before. Thus, it is unclear what type of source RE J1255+266 might be. Up to now no positive identification with any known source could be obtained. Emission at the position of the source was previously only detected in the 1987 Green Bank radio continuum survey. Simultaneous observations with Compton Gamma Ray Observatory/Burst and Transient Source Experiment (CGRO/BATSE) resulted in non-detections of the source in the 8 - 50 keV energy range.
Dahlem, M.↗