Typescript
Topics: Quasars, Radio sources (Astronomy)
Typescript
Topics: Quasars, Radio sources (Astronomy)
Typescript
Topics: Radio sources (Astronomy), Interstellar matter
247
247
Oct 4, 2012
10/12
by
Lawrence, Robert Standish, 1925-
texts
eye 247
favorite 0
comment 0
Topics: Radio astronomy., Radio sources (Astronomy)
4
4.0
texts
eye 4
favorite 0
comment 0
xvii, 490 p. : 25 cm
Topics: Radio sources (Astronomy) -- Congresses, Galaxies -- Congresses
3
3.0
texts
eye 3
favorite 0
comment 0
xii, 345 p. : 25 cm
Topics: Cosmology -- Observations -- Congresses, Radio sources (Astronomy) -- Observations -- Congresses
3
3.0
texts
eye 3
favorite 0
comment 0
xi, 411 p. : 25 cm
Topics: Radio sources (Astronomy) -- Congresses, Stars -- Radiation -- Congresses, Radio astrophysics --...
637
637
Jun 21, 2010
06/10
by
NON
texts
eye 637
favorite 0
comment 0
Apollo mission 11 trajectory reconstruction and postflight analysis
Topics: INTERFEROMETRY, OCCULTATION, RADIO SOURCES (ASTRONOMY), RELATIVISTIC EFFECTS, FREQUENCY STANDARDS,...
255
255
Jul 6, 2010
07/10
by
LEGENDRE, R
texts
eye 255
favorite 0
comment 0
THE KUTTA-JOUKOWSKY CONDITION IN THREE DIMENSIONAL FLOW IS DISCUSSED. THE CHARACTERISTICS OF THE SEPARATION LINE ALONG WHICH A VORTEX SHEET IS ATTACHED ON A WING ARE EXAMINED. FROM OBSERVATIONS OF THE FLOW OVER MARINE PROPELLERS AND DELTA WING MODELS, A DISCUSSION IS PRESENTED TO IMPROVE THE DESCRIPTION OF THE FLOW OVER ANY WING AND TO PROVIDE A BETTER BASIS FOR ACCURATE CALCULATIONS OF THE PERFECT FLUID FLOW USED AS A REFERENCE.
Topics: QUASARS, RADIO INTERFEROMETERS, RADIO STARS, BRIGHTNESS TEMPERATURE, RADIO ASTRONOMY, RADIO SOURCES...
301
301
Jun 21, 2010
06/10
by
NON
texts
eye 301
favorite 0
comment 0
Development and implementation of communications equipment for Deep Space Instrumentation Facility
Topics: INTERSTELLAR COMMUNICATION, RADIO SOURCES (ASTRONOMY), COMMUNICATION THEORY, DECODING,...
443
443
Jul 11, 2010
07/10
by
Proverbio, E.; Quesada, V.; Simoncini, A
texts
eye 443
favorite 0
comment 0
Relative comparisons of Loran-C frequency transmissions between the master station of Catanzaro (Simeri Crichi) and the X, Z slave stations of Estartit (Spain) and Lampedusa (Italy) are carrying out by the GG LORSTA monitor station of the Mediterranean Sea Loran-C chain. These comparisons are able to emphasize the relative and, under certain conditions, the absolute rate of the emitting standard frequencies of the slave stations and some relevant statistical properties of the Loran-C Method for...
Topics: CLOCKS, DEEP SPACE NETWORK, RADIO INTERFEROMETERS, SYNCHRONISM, DATA TRANSMISSION, LORAN C, RADIO...
178
178
Jul 12, 2010
07/10
by
NON
texts
eye 178
favorite 0
comment 0
The CEAS models evaluated use historic trend and meteorological and agroclimatic variables to forecast soybean yields in Iowa, Illinois, and Indiana. Indicators of yield reliability and current measures of modeled yield reliability were obtained from bootstrap tests on the end of season models. Indicators of yield reliability show that the state models are consistently better than the crop reporting district (CRD) models. One CRD model is especially poor. At the state level, the bias of each...
Topics: DEEP SPACE NETWORK, MICROWAVES, RADIO INTERFEROMETERS, RADIO SOURCES (ASTRONOMY), COMMUNICATION...
This report summarizes the activities of the United States Naval Observatory Analysis Center for Source Structure for calendar year 2006. VLBA RDV experiments RDV57 and RDV59 were calibrated and imaged. VLBA high frequency experiment BL122C was calibrated and imaged. Images from these three experiments, together with images from RDV16 and RDV23 were added to the USNO Radio Reference Frame Image Database. A Southern Hemisphere imaging and astrometry program for maintenance of the ICRF continued....
Topics: DTIC Archive, NAVAL OBSERVATORY WASHINGTON DC, *RADIO SOURCES(ASTRONOMY), MAPPING, RADIO...
1,087
1.1K
Jul 11, 2010
07/10
by
NON
texts
eye 1,087
favorite 0
comment 0
For abstract, see N75-18672.
Topics: EXPLORER 49 SATELLITE, RADIO ASTRONOMY, SATELLITE-BORNE INSTRUMENTS, LUNAR OCCULTATION, LUNAR...
463
463
Jul 11, 2010
07/10
by
Sherman, H. T
texts
eye 463
favorite 0
comment 0
A program is in progress to implement coordinated universal time (UTC) synchronization on all Loran-C transmissions. The present capability is limited to five Loran-C chains in which the tolerance is twenty-five microseconds with respect to UTC. Upon completion of the program, the transmissions of all Loran-C chains will be maintained within five microseconds of UTC. The improvement plan consists of equipping selected Loran-C transmitting stations for greater precision of frequency standard...
Topics: GEODESY, RADIO INTERFEROMETERS, RADIO NAVIGATION, SHIPS, EARTH ATMOSPHERE, POSITION (LOCATION),...
6
6.0
texts
eye 6
favorite 1
comment 0
xv,361p
Topics: Very long baseline interferometry, Radio sources (Astronomy), Radio sources Observation...
Direct resolution of Cygnus A at a frequency of 3292 Mc/s using the 52 inch fan beam of a compound interferometer is reported. On the basis of a firm determination of the actual peak-to-peak distance the existing data were examined and it was found that the reported dependence of separation on frequency is simply an appearance produced by the existence of a third-component whose spectrum differs from that of the main components.
Topics: DTIC Archive, Swarup, G, STANFORD UNIV CA, *RADIO ASTRONOMY, *RADIO SOURCES(ASTRONOMY), PARABOLAS,...
288
288
Jul 11, 2010
07/10
by
Peters, H. E
texts
eye 288
favorite 0
comment 0
In house research and development at Goddard Space Flight Center to provide advanced frequency and time standards for the most demanding applications is concentrated primarily in field operable atomic hydrogen masers. Some of the most important goals for the new maser designs have been improved long and short term stability, elimination of the need for auto tuning, increased maser oscillation level, improved hydrogen economy, increased operational life, minimization of operator control or...
Topics: ASTROMETRY, UNIVERSAL TIME, GEODESY, RADIO INTERFEROMETERS, TIME MEASUREMENT, CLOCKS, FREQUENCY...
Although rapid reorientation of a black hole spin axis (lasting less than a few Myr) has been suggested as a mechanism for the formation of wings in X-shaped radio galaxies (XRGs), to date no convincing case of reorientation has been found in any XRG. Alternative wing formation models such as the hydrodynamic backflow models are supported by observed trends indicating that XRGs form preferentially with jets aligned along the major axis of the surrounding medium and wings along the minor axis....
Topics: DTIC Archive, MARYLAND UNIV COLLEGE PARK DEPT OF ASTRONOMY, *GALAXIES, WINGS, RADIO...
One of the defining characteristics of BL Lacertae objects is their strong variability across the electromagnetic spectrum. PKS 0537-441 is one such object and is one of the most luminous blazars from radio to gamma-ray wavelengths. It was detected as a strong and highly variable source by EGRET and has been reported several times to be in an active state by Fermi . It is one of the brightest gamma-ray blazars detected in the southern sky so far. The TANAMI (Tracking Active Galactic Nuclei with...
Topics: DTIC Archive, NAVAL OBSERVATORY WASHINGTON DC, *GAMMA RAYS, *RADIO SOURCES(ASTRONOMY), *QUASARS,...
271
271
Jul 12, 2010
07/10
by
Fu, L. S
texts
eye 271
favorite 0
comment 0
The problem of establishing a theoretical groundwork for experimentally-found correlations between ultrasonic and fracture toughness factors in polycrystalline metals is discussed. It is noted that the link between these material properties and ultrasonic factors are the microstructural parameters that interact with stress wave propagation during deformation and fracture. The dynamic response of material inhomogeneities and the strains and displacements they undergo under incident stress waves...
Topics: ERROR ANALYSIS, RADIO INTERFEROMETERS, RADIO SOURCES (ASTRONOMY), TIME MEASUREMENT, FOURIER...
The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei...
Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV, *QUASARS, GALAXIES, GAMMA RAYS,...
The utilization of conventional and VLBI interferometer techniques for accurate determination of UTI, polar motion, and radio source position catalog data is discussed.
Topics: NASA Technical Reports Server (NTRS), ASTROMETRY, INTERFEROMETERS, UNIVERSAL TIME, ACCURACY,...
We report new radio imaging of the large-scale radio structure of M87 with the VLA at 90 cm. These new images show the complex structure of the radio emission more clearly than previous attempts, some of which date back to the 1940s. The images suggest that the outward flow from the M87 nucleus extends well beyond the 2 kpc jet. Two bubbles of synchrotron emission appear to be inflated by this flow. A simple model of the emission, combined with our knowledge of the inner jet, suggest that the...
Topics: DTIC Archive, Owen, Frazer N, NATIONAL RADIO ASTRONOMY OBSERVATORY SOCORRO NM, *RADIOFREQUENCY,...
9
9.0
Jun 27, 2020
06/20
by
Pacholczyk, A. G., 1935-
texts
eye 9
favorite 1
comment 0
xi, 293 pages : 26 cm
Topics: Radio galaxies, Radiosources, Galaxies, Radiogalaxie, Galaxie, Kosmische Strahlung,...
The time domain of the sky has been only sparsely explored. Nevertheless, recent discoveries from limited surveys and serendipitous discoveries indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenonmena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have found not-yet identified radio transients without optical or...
Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC, *SKY, OPTICAL PROPERTIES, RADIO SOURCES(ASTRONOMY),...
249
249
Jul 12, 2010
07/10
by
NON
texts
eye 249
favorite 0
comment 0
All users of the NAVSTAR Global Positioning System (GPS) located within a rather large geographical area are currently required to perform a number of identical, common operations in order to accomplish a navigation ''fix'' (additional ''location dependent'' operations are also required). Under the REFSAT concept, the common operations are performed at a central location and results broadcast via a geostationary reference satellite (REFSAT). This concept allows a considerable reduction in the...
Topics: FLICKER, NOISE PROPAGATION, RADIO SOURCES (ASTRONOMY), TIME MEASUREMENT, DEEP SPACE NETWORK,...
X-shaped radio galaxies are defined by their peculiar large-scale radio morphology. In addition to the classical double-lobed structure they have a pair of low-luminosity wings that straddles the nucleus at almost right angles to the active lobes, thus giving the impression of an 'X'. In this paper we study for the first time the optical spectral properties of this object class using a large sample ( 50 sources). We find that the X- shaped radio population is composed roughly equally of sources...
Topics: DTIC Archive, MELBOURNE UNIV PARKVILLE (AUSTRALIA) SCHOOL OF PHYSICS, *GALAXIES, OPTICAL...
Observations of the 8.35 mm radio emission from Jupiter and Venus are reported. A disc temperature of 144 = 23 deg. is found for Jupiter and a temperature of 383 = 60 deg. is found for Venus. It is shown that the 8 mm brightness temperature of Jupiter should correspond closely to the temperature at the level of the visible cloud cover.
Topics: DTIC Archive, CALIFORNIA UNIV BERKELEY SPACE SCIENCES LAB, *MILLIMETER WAVES, *RADIO...
269
269
Jul 5, 2010
07/10
by
Mayo, F. R
texts
eye 269
favorite 0
comment 0
The curing and decompositions of polyphenylenes and several nitrogen-containing condensation polymers, particularly polybenzimidazoles and pyrones, are reviewed critically. It is concluded that the condensations are usually imperfect and incomplete and that in most of the published work the late stages of the condensation are complicated by the beginnings of the charring and carbonization processes. Most discussions of mechanisms in this range are highly speculative and of little value. The...
Topics: NEBULAE, X RAY ABSORPTION, X RAY ASTRONOMY, BREMSSTRAHLUNG, CONFERENCES, RADIATION SOURCES, RADIO...
A differential astrometry technique is discussed. An improved proper motion and a parallax limit for pulsar 1929 + 10 is presented as well as a limit on the space velocity of the enigmatic object in SgrA.
Topics: NASA Technical Reports Server (NTRS), ASTROMETRY, PARALLAX, RADIO SOURCES (ASTRONOMY), VELOCITY...
G359.87 + 0.18 is an enigmatic object located 15' from Sgr A*. It has been variously classified as an extragalactic source, a Galactic jet source, and a young supernova remnant. We present new observations of G359.87 + 0.18 between 0.33 and 15 GHz and an H I absorption spectrum and use these to argue that this source is an FR II radio galaxy. We are able to place a crude limit on its redshift of z / 0.1. The source has a spectral index of alpha -1(S proportional to va), suggestive of a radio...
Topics: DTIC Archive, Lazio, T J, NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV, *GALAXIES, *FLUX...
This report describes all the projects undertaken during the entire period of the above contract, the scope of which was to study coronal holes at radio wavelengths. Chapters 1, 2 and 3 summarize work that has already been described in our previous scientific reports and published papers. Chapters 4 and 5 and comprehensive descriptions of the more recent work that has not been previously published. Chapter 1 describes the determination of the radio spectrum (relative changes in the brightness...
Topics: DTIC Archive, Papagiannis,Michael D, *SOLAR CORONA, *SOLAR RADIO MAPS, GRAPHS, TABLES(DATA), RADIO...
New radio data at 330 MHz are presented for the rich clusters Abell 665 and Abell 2163, whose radio emission is characterized by the presence of a radio halo. These images allowed us to derive the spectral properties of the two clusters under study. The integrated spectra of these halos between 0.3 GHz and 1.4 GHz are moderately steep: varies as 1.4/0.3 = 1.04 and varies as 1.4/0.3 = 1.18, for A665 and A2163, respectively. The spectral index maps, produced with an angular resolution of the...
Topics: DTIC Archive, Feretti, L, INSTITUTE OF RADIO ASTRONOMY (IRA) BOLOGNA (ITALY), *GALAXIES, MAGNETIC...
The machine readable catalogue contains survey data from the papers of Pilkington and Scott and Gower, Scott and Wills. These data result from a survey of radio sources between declinations -07 deg and +80 deg using the large Cambridge interferometer at 178 MHz. The computerized catalog contains for each source the 4C number, 1950 position, measured flux density, and accuracy class. For some sources miscellaneous brief comments such as cross identifications to the 3C catalog or remarks on...
Topics: NASA Technical Reports Server (NTRS), CATALOGS (PUBLICATIONS), DATA BASES, RADIO SOURCES...
High resolution, low frequency observations are very efficient for surveying radio galaxies because of: 1) the wide field of view and 2) the bias toward steep spectrum (lobe dominated) emission. Here I present preliminary results from two ongoing low frequency radio surveys: the 4 Meter All Sky Survey (4MASS) and the low frequency counterpart to the XMM-Large Scale Structure (XMM-LSS) survey. 4MASS is an NRL-NRAO project to survey the entire sky above delta = -20 degrees at 74 MHz with a...
Topics: DTIC Archive, Cohen, A S, NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV, *SURVEYS, *LOW...
Milliarcsecond-accurate radio positions for 25 southern hemisphere extragalactic sources are reported. These positions are derived from Mark III Very Long Baseline Interferometry observations made between 2003 September and 2004 May on the intra-Australia baseline connecting Hobart, Tasmania and Parkes, New South Wales. The results presented here represent an ongoing program intended to increase the number of phase reference sources with accurate positions in the southern hemisphere for use in...
Topics: DTIC Archive, Fey, Alan L, NAVAL OBSERVATORY WASHINGTON DC, *RADIO ASTRONOMY, *RADIO...
355
355
Jul 11, 2010
07/10
by
Martin, R. R.; Warr, G. A.; Putman, M. J.; Kentor, D. H.; Holleman, C. L
texts
eye 355
favorite 0
comment 0
The possible effects of space flight and weightlessness on polymorphonuclear leukocyte (PMN) function, the body's defense against bacterial infection, were investigated in terms of space flight of long duration. Serial blood samples obtained from crewmembers of the ASTP and normal control subjects were tested for total leukocyte count, differential count, leukocyte migration and chemotaxis, phagocytic ability, and cytoplasmic granules stained for leukocyte acid and alkaline phosphatase. The...
Topics: APOLLO SOYUZ TEST PROJECT, RADIATION SOURCES, RADIO SOURCES (ASTRONOMY), ULTRAVIOLET SPECTRA,...
The requirements in hardware, manpower, time and funding to conduct a realistic effort aimed at detecting the existence of extraterrestrial intelligent life are examined. The methods used are limited to present or near term future state-of-the-art techniques. Subjects discussed include: (1) possible methods of contact, (2) communication by electromagnetic waves, (3) antenna array and system facilities, (4) antenna elements, (5) signal processing, (6) search strategy, and (7) radio and radar...
Topics: NASA Technical Reports Server (NTRS), EXTRATERRESTRIAL LIFE, EXTRATERRESTRIAL RADIO WAVES, RADIO...
The bright and highly variable X-ray and radio source known as Cygnus X-3 was among the first X-ray sources discovered, yet it remains in many ways an enigma. Its known to consist of a massive, Wolf-Rayet primary in an extremely tight orbit with a compact object. Yet one of the most basic of parameters - the mass of the compact object - is not known. Nor is it even clear whether its is a neutron star or a black hole. In this Paper we present our analysis of the broad-band high-energy continua...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIGHT...
We present an overview of precise pulsar timing using data from the Large Area Telescope (LAT) on Fermi. We describe the analysis techniques including a maximum likelihood method for determining pulse times of arrival from unbinned photon data. In addition to determining the spindown behavior of the pulsars and detecting glitches and timing noise, such timing analyses allow the precise determination of the pulsar position, thus enabling detailed multiwavelength follow up.
Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC, *PULSARS, *TIME SERIES ANALYSIS, RADIO TELESCOPES,...
A list of linear polarization measurements for 66 radio sources is presented. It includes values for 39 sources not previously reported on, plus a more complete set of values for sources previously described. Of these sources, approximately 40 have been examined at three different warelengths (10, 18 and 21 cm) and for those with appreciable polarization in this range the dependence of polarization on wavelength is given. The relationship between the major axis position angle and the intrinsic...
Topics: DTIC Archive, Morris, D, OWENS VALLEY RADIO OBSERVATORY PASADENA CA, *POLARIZATION, *RADIO SIGNALS,...
We present here the results of a 325 MHz radio survey of M31, conducted with the A configuration of the Very Large Array (VLA). The survey covered an area of 7.6 deg2, and a total of 405 radio sources were mapped. For each source, its morphological class, major axis, minor axis, position angle, peak flux, integrated flux density, spectral index, and spectral curvature parameter were calculated. A comparison of the flux and radial distribution both in the plane of the sky and in the plane of M31...
Topics: DTIC Archive, Gelfand, Joseph D, HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS CAMBRIDGE MA, *RADIO...
We present new, low-frequency images of the powerful FR I radio galaxy Hydra A (3C 218). Images were made with the Very Large Array at frequencies of 1415, 330, and 74 MHz, with resolutions on the order of 20. The morphology of the source is seen to be more complex and even larger than previously known and extends nearly 8' (530 kpc) in a north-south direction. The southern lobe is bent to the east and extends in that direction for nearly 3' (200 kpc). In addition, we find that the northern...
Topics: DTIC Archive, Lane, W M, NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV, *IMAGES, *LOW...
The ICRF2 catalog was constructed by the IERS/IVS Working Group with oversight by the IAU Working Group. Derived using data from August 1979 through March 2009, it is a great improvement over the original ICRF with 3414 extragalactic radio source positions, a noise floor of 40 microarcsec, and axis stability of 10 microarcsec. Significant refinements were made in the selection of defining sources, modeling, and the integration of CRF, TRF, and EOP. The adoption of the ICRF2 was approved by the...
Topics: NASA Technical Reports Server (NTRS), CELESTIAL REFERENCE SYSTEMS, RADIO SOURCES (ASTRONOMY), VERY...
To date there have been 10 VLBI experiments observed over a period spanning 5 years and analyzed for the purpose of establishing a high-frequency (24 GHz) reference frame. The database now contains information on 274 sources and a total of 1052 images. From the data, we have produced a high-frequency astrometric catalog of 266 sources. Of these 266 sources, 88 of them have been observed in at least five epochs. We produced time series of source positions for each of the 88 sources and compare...
Topics: DTIC Archive, Boboltz, D A, NAVAL OBSERVATORY WASHINGTON DC, *TIME SERIES ANALYSIS,...
Why source structure affects VLBI observations and how source structure corrupts the geodetic observables are discussed. Evidence is presented which shows that corrections for source structure are possible and necessary for centimeter level accuracy VLBI measurements.
Topics: NASA Technical Reports Server (NTRS), GEODESY, POINT SOURCES, RADIO SOURCES (ASTRONOMY), VERY LONG...
The quantitative response of the Planetary Radio Astronomy (PRA) instrument to a wave with polarization ellipse of arbitrary shape and orientation, arriving at the antennas from any direction, can be determined. This capability is used to model the time variation of intensity and circular polarization over a range of radio frequencies for proposed radio-source locations and emission characteristics at Neptune. At frequencies below 400 kHz the observed variation of intensity, polarization, and...
Topics: NASA Technical Reports Server (NTRS), CIRCULAR POLARIZATION, NEPTUNE (PLANET), RADIO ASTRONOMY,...
The previous bibliography is extended to include abstracts of articles published in 1950. The sections deal with the literature concerning solar radiation, general galactic radiation, radiation from discrete sources, lunar radiation, and miscellaneous radiation. Observations, theories, and interpretations are presented. Each section is alphabetized by author.
Topics: DTIC Archive, Carpenter, Martha S., CORNELL UNIV ITHACA NY SCHOOL OF ELECTRICAL ENGINEERING, *RADIO...
The prototype system for Deep Space Network clock synchronization by VLBI has been demonstrated to operate successfully over intercontinental baselines in a series of experiments between Deep Space Stations at Madrid, Spain, and Goldstone, California. As predicted by analysis and short baseline demonstration, the system achieves reliable synchronization between 26m and 64m antenna stations with 17 and 37K nominal system temperatures using under one million bits of data from each station....
Topics: NASA Technical Reports Server (NTRS), CLOCKS, DEEP SPACE NETWORK, RADIO INTERFEROMETERS,...
