Search NASA⌕ Search

SEARCH · Search NASA

Results for “radio detection”

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.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

A note on the acceleration phase of high-energy particles in the solar flare on 7 July, 1966.

The acceleration phase of solar cosmic rays and relativistic electrons is studied on the basis of the observational data available on the optical, radio, X-ray, and particle events associated with the solar flare that occurred on July 7, 1966. The generating process of hydromagnetic shock waves which excited the type-II radio burst detected at a frequency below about 100 MHz is also discussed. The results of the study suggest that no secondary acceleration process after the explosive phase can contribute much to the generation of high energy particles. The ejection of solar cosmic rays and relativistic electrons seems to be related to the expansion of the magnetic bulge which can trap accelerated electrons from the triggering region of solar flares.

Sakurai, K.↗
NASA NTRS1974

Short-duration radio flares of UV Ceti stars

The UV Ceti-type stars YZ Canis Minoris, AD Leonis, Wolf 424, and V371 Orionis were monitored with the Arecibo radio telescope at meter wavelengths. A total of 26 flares were recorded on YZ CMi, AD Leo, and Wolf 424. The observed flares had shorter durations and smaller amplitudes than those previously reported in the literature. Rates of radio-flare detection are similar to those found optically.

Spangler, S. R.↗
NASA NTRS1977

Radio and optical observations in the fields of five unidentified X-ray sources at high latitudes

Radio observations at 610 MHz and optical plates were obtained for five fields centered on the unidentified X-ray sources 3U0042 + 32, 3U0917 + 63, 3U1443 + 43, 3U1555 + 27, and 3U1809 + 50. For the first three fields, several radio sources are found which are associated with stellar objects within or near the X-ray error boxes. A 'tailed' radio galaxy has been found in Abell 2142, and this cluster is suggested as the identification for 3U1555 + 27. Although there are no radio sources greater than 0.1 flux unit within the X-ray error boxes associated with 3U1809 + 50, a Zwicky cluster surrounding the 3U position contains two radio galaxies: one with an inverted spectrum and another with a wide-angle tail. A table of positions, intensities, and suggested optical identifications is given for the 249 radio sources detected in the five fields.

Harris, D. E.↗
NASA NTRS1979

Technique to determine location of radio sources from measurements taken on spinning spacecraft

The procedure developed to extract average source direction and average source size from spin-modulated radio astronomy data measured on the IMP-6 spacecraft is described. Because all measurements are used, rather than just finding maxima or minima in the data, the method is very sensitive, even in the presence of large amounts of noise. The technique is applicable to all experiments with directivity characteristics. It is suitable for onboard processing on satellites to reduce the data flow to Earth. The application to spin-modulated nonpolarized radio astronomy data is made and includes the effects of noise, background, and second source interference. The analysis was tested with computer simulated data and the results agree with analytic predictions. Applications of this method with IMP-6 radio data have led to: (1) determination of source positions of traveling solar radio bursts at large distances from the Sun; (2) mapping of magnetospheric radio emissions by radio triangulation; and (3) detection of low frequency radio emissions from Jupiter and Saturn.

Fainberg, J.↗
NASA NTRS1979

Plasma wave observations near Jupiter - Initial results from Voyager 2

The Voyager 2 flyby of Jupiter, which occurred in July 1979, provided the second opportunity to study plasma waves in the vicinity of Jupiter (first measurements made by Voyager 1 in March 1979). Because of the somewhat different trajectory and plasma conditions at Jupiter, the Voyager 2 mission provided new perspectives for analyzing many of the phenomena detected by Voyager 1, and also revealed the presence of several new types of plasma waves. A survey is presented of the initial results from the Voyager 2 plasma wave instrument, with special emphasis on the new observations and comparisons with the Voyager 1 results. The data base for the present discussion starts with the first detection of radio emissions from Jupiter about six months before closest approach and ends about two weeks after closest approach

Gurnett, D. A.↗
NASA NTRS1980

Lightning on Jupiter - Rate, energetics, and effects

Voyager data on the optical and radio-frequency detection of lightning discharges in the atmosphere of Jupiter suggest a stroke rate significantly lower than on the earth. The efficiency of conversion of atmospheric convective energy flux into lightning is almost certainly less than on the earth, probably near 10 to the -7th rather than the terrestrial value of 10 to the -4th. At this level the rate of production of complex organic molecules by lightning and by thunder shock waves is negligible compared to the rates of known photochemical processes for forming colored inorganic solids.

Lewis, J. S.↗
NASA NTRS1982

Detection of X-rays during the outburst of supernova 1980k

X-ray emission from SN 1980k in NGC 6946 was detected about 35 days after maximum light using the imaging proportional counter on the Einstein Observatory. The absorption corrected X-ray flux of SN 1980k was about 0.03 micro-Jy at 0.24 x 10 to the 18th Hz (1 keV), which corresponds to a luminosity of about 2 x 10 to the 39th ergs/s (0.2-4 keV) at 10 Mpc. This detection of radio emission suggests the presence of relativistic electrons and a magnetic field strength of not greater than about 1 gauss. Inverse Compton scattering of the optical photons on the electrons can explain the X-ray emission without additional ad hoc assumptions, although other emission mechanisms are possible.

Canizares, C. R.↗
NASA NTRS1982

The source of Saturn electrostatic discharges

During both Voyager encounters with the saturnian system, the Planetary Radio Astronomy experiment detected strong discrete episodic bursts of radio emission, termed Saturn electrostatic discharges (SED). An examination of Voyager 2 photopolarimeter data now reveals a narrow feature (possibly a gap) in Saturn's B ring. A single, unique object appears to be responsible for both the SED and this feature.

Evans, D. R.↗
NASA NTRS1984

Microwave Radiation Detector

Direct photon detector responds to microwave frequencies. Method based on trapped-ion frequency-generation standards proposed to detect radio-frequency (RF) radiation at 40.5 GHz. Technique used for directdetection (RF) communication, radar, and radio astronomy.

Lesh, J. R.↗
NASA NTRS1983

Coordinate systems

Jovian coordinate systems are different from those employed in the case of the earth. Latitude and longitude coordinates are usually established relative to some solid surface. Because Jupiter does not have a solid surface (at least none which is visible through the clouds), arbitrary, but convenient, coordinate grids have been prescribed. A spin equator is made out from observations of cloud motion, and the direction of the planetary spin axis is, therefore, determined with relatively good accuracy. The problem in establishing a Jupiter longitude system is that the mean rotation period of the clouds is a function of latitude. The solution selected was to define two separate longitude grids. A third longitude system became necessary with the detection of radio signals which gave evidence for a rotating planetary magnetic field. Attention is also given to orbital phase angle and longitude conventions for satellites, and two latitude systems for Jupiter

Dessler, A. J.↗
NASA NTRS1983

X-rays from jets and lobes

The current status of X-ray detections (and non-detections) of radio jets and lobes is presented. High resolution images obtained with the Einstein Observatory reveal X-ray emission associated with jet and lobe components of Virgo A, Centaurus A, 3C273, and possibly other radio structures. The Vir A and Cen A jet emission is probably s ynchrotron in origin, requiring in situ particle acceleration to extremely high energies. Inverse Compton emission is the likely cause of asymmetrical X-ray features in the halo of Vir A, supporting the assumption of equipartition.

Feigelson, E. D.↗
NASA NTRS1986

A VLA survey of unidentified HEAO-1 X-ray sources

Radio observations toward 47 unidentified sources from the HEAO-1 all-sky X-ray survey (Wood et al., 1984), obtained at 1.418 GHz using the C configuration of the VLA on May 11-14, 1983 are reported. Of the 238 radio sources detected at flux density 1-3 mJy or greater, 26 are found to be within 5 arcsec of optical objects, which are thereby considered to be candidate X-ray sources. Tentative classifications of the candidates include five RS CVn systems, three AGNs, three galaxy or cluster sources, and two X-ray binaries.

Schmelz, J. T.↗
NASA NTRS1987

The sources of Uranus' dominant nightside radio emissions

The broad-bandwidth radio emission detected by Voyager 2 over the nightside of Uranus is examined. It is concluded that the source location of the smooth component is consistent with emission originating near the electron gyrofrequency from a small set of field lines whose foot points lie near the Uranomagnetic southern (dark) pole. The source centroid is at L = 11.5, and extends in latitude between about L = 8 and L = 25. This deduced source region is primarily on closed field lines that pass through the outer radiation belt and have their opposite foot points near the Uranomagnetic northern pole (near the present epoch terminator). The source location of the bursty component is less well defined but is consistent with the set of open field lines which map down to the region surrounding the planet's south magnetic dipole tip.

Kaiser, M. L.↗
NASA NTRS1989

Optically-Controlled Microwave Devices And Circuits

NASA Technical Memorandum discusses physical basis and dc and microwave characteristics of optically-controlled microwave devices described in literature. Emphasis on responses of GaAs/GaAlAs high-electron-mobility transistors (HEMT's) and GaAs metal/semiconductor field-effect transistors (MESFET's) to light. Devices used to detect radio-frequency modulation of optical signals, to control gains of amplifiers, and to provide injection locking of oscillators.

Bhasin, Kul B.↗
NASA NTRS1988

A solar-wind 'trigger' for the outer heliosphere radio emissions and the distance to the terminal shock

The solar wind data from the plasma science experiment on the Voyager spacecraft are examined to search for the source of the 2 to 3 kHz radio noise detected in the outer heliosphere. It is found that two anomalous high speed streams passed Voyager 2 before the noise was initially observed. It is suggested that the interaction of these streams with the terminal shock is responsible for the more intense emission. Using a time-of-flight argument, the distance to the shock is estimated at about 70 AU-140 AU. The larger value is consistent with an estimate using Voyager data and a standard pressure-balance argument.

Mcnutt, Ralph L., Jr.↗
NASA NTRS1989

Ly-alpha emission from disk absorption systems at high redshift - Star formation in young galaxy disks

Narrow-band imaging observations are reported which were made in an attempt to detect Ly-alpha emission from high-redshift candidate galaxy disk systems discovered as high column density absorbers of background QSOs. For four systems with z = 2.3-2.8, no emission is detected to a limit of about 10 to the -16th ergs/sq cm/s, corresponding to luminosity limits of about 10 exp 42-43 ergs/s for the material producing the absorption. The inferred Ly-alpha luminosities lie one to two orders of magnitude below estimates of the Ly-alpha luminosities for active star-forming epochs of many prescriptions for galaxy formation and also considerably below measured Ly-alpha luminosities for other candidate young galaxies detected in radio surveys. A limiting star-formation rate in these systems of about 2-7 solar masses/yr is set; the limit may be about 10 times larger with small but observationally allowable amounts of dust.

Smith, Harding E.↗
NASA NTRS1991

An anomalous component of Neptune radio emission - Implications for the auroral zone

The Voyager planetary radio astronomy experiment detected a bursty, narrow-band radio emission originating in Neptune's magnetosphere. The time of occurrence of nearly all of the episodes of this bursty radio emission can be explained on the basis of a radio source located just above and to the east of the south magnetic offset tilted dipole (OTD) tip (Farrell et al., 1990). However, several episodes of bursty emission do not occur at the usual frequency and planetaray rotation phase for emissions of this type. The occurrences of these rarely seen anomalous episodes are shifted systematically in planetary longitude so as to be consistent with a source of emission to the southwest of the southern magnetic OTD pole. Owing to the proximity of these sources to the magnetic polar region, they are associated with an active auroral region. Therefore, at least from the standpoint of the radio emission, the picture that emerges is of an auroral zone with two emission hot spots approximately diametrically east and west of the south magnetic pole. The possibility of a complete radio-active auroral oval is discussed.

Desch, M. D.↗
NASA NTRS1992

Ulysses observations of escaping VLF emissions from Jupiter

The Ulysses URAP experiment has detected Jovian radio emissions in the VLF range at distances from Jupiter in excess of 1.5 AU. The URAP observations represent the first synoptic observations of Jupiter in the VLF band, from 3 to 30 kHz. In this band lie the low-frequency extent of the bKOM emission, the escaping continuum emission, and the Jovian type IIIs. Initial results indicate that the continuum varies in frequency with the solar wind ram pressure at Jupiter, whereas, the Jovian type IIIs appear to be controlled to some extent by the planetary rotation, often appearing when system III longitude 100 deg faces the spacecraft.

Kaiser, M. L.↗