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At least 865 records · Page 48
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NASA NTRS1972

X-ray emission from the galactic disk

A search was made of a diffuse component of X-rays 1.5 keV associated with an interarm region of the galaxy at galactic longitudes in the vicinity of 60 deg. A statistically significant excess associated with a narrow disk component was detected. The angular extent of this component has a most probable value of 2 deg and may be as large as 7 deg at 90% confidence. The best fit spectrum yields an intensity of 2.9 photons 1/(cm2-sec-ster) over the 2 to 10 keV range. The 3 sigma upper limit to any emission (e.g. iron line) in a 1.5 keV band centered at 7 keV from galactic latitudes h or = 3.5 deg is .3 photons 1/(cm2-sec-ster). Several possible emission models are discussed, with the most likely candidate being a population of unresolvable low luminosity discrete sources.

Bleach, R. D.↗
NASA NTRS1972

The particles and fields subsatellite magnetometer experiment

A preliminary analysis of magnetometer data from Apollo 15 subsatellite is concluded. Remanent magnetization is a characteristic property of the moon, and the distribution is such that a complex pattern is produced. A mapping of the distribution is feasible with the present experiment. Lunar induction fields produced by transients in interplanetary magnetic field are detectable at satellite orbit. Magnetometer data will provide estimates of the latitude and longitude dependences of interior conductivity. The plasma void extends to some altitude below the satellite orbit and probably the lunar surface. Solar wind near the limbs is usually strongly disturbed.

Coleman, P. J., Jr.↗
NASA NTRS1972

A study of 2-20 KeV X-rays from the Cygnus region

Two rocket-borne proportional counters, each with 650 sq c, met area and 1.8 x 7.1 deg FWHM rectangular mechanical collimation, surveyed the Cygnus region in the 2 to 20 keV energy range on two occasions. X-ray spectral data gathered on 21 September 1970 from discrete sources in Cygnus are presented. The data from Cyg X-1, Cyg X-2, and Cyg X-3 have sufficient statistical significance to indicate mutually exclusive spectral forms for the three. Upper limits are presented for X-ray intensities above 2 keV for Cyg X-4 and Cyg X-5 (Cygnus loop). A search was made on 9 August 1971 for a diffuse component of X-rays 1.5 keV associated with an interarm region of the galaxy at galactic longitudes in the vicinity of 60 degrees. A statistically significant excess associated with a narrow disk component was detected. Several possible emission models are discussed, with the most likely candidate being a population of unresolvable low luminosity discrete sources.

Bleach, R. D.↗
NASA NTRS1972

An atlas of low latitude 6300A (01) night airglow from OGO-4 observations

The atomic oxygen emission line at 6300 A, measured in the nadir direction by a photometer on the polar orbiting satellite OGO-4, was plotted between 40 deg N and 40 deg S latitude on a series of maps for the moon-free periods between 30 August 1967 and 10 January 1968 The longitudinal and local time variations which occur during the northern fall-winter season are indicated. The northern tropical arc is more widespread while the southern arc is not present at all longitudes. The conditions under which the observations were made are described, and four airglow maps were selected to show the local time variations.

Reed, E. I.↗
NASA NTRS1972

World maps of predicted electron intensities for the ITOS-A/NOAA-1 spacecraft

Maps of electron fluxes 10,000, 1 million, and 10 million particles/sq cm/sec are presented for an ITOS-A/NOAA-1 circular orbit, inclination of 79 deg, and altitude of 1463 km. The uncertainty in the flux values is about a factor of 3, and the error in contour plotting may be plus or minus 2 deg in latitude and plus or minus 3 deg in longitude. The fractional lifetime spent within the different intensity regions is graphed.

Stassinopoulos, E. G.↗
NASA NTRS1972

Atlas of electron content values observed at Urbana, Illinois, 1 December 1967 - 30 December 1970

Ionospheric electron content versus local time data deduced from Faraday rotation observations of ATS-III geostationary satellite signals at Urbana, Illinois are reported. The data are presented in two forms. Values of subionospheric latitude (SILAT) and subionospheric longitude (SILON) are in degrees north and degrees west, respectively. These are computed on the basis of 350 km for the mean ionospheric height, which value is also used for the calculation of the geometric-magnetic factor, required for the conversion of the measured Faraday rotation angle to electron content. Entries of zero for the electron content in the tables represent no data for those times.

Flaherty, B. J.↗
NASA NTRS1972

Why does the sun sometimes look like a magnetic monopole?

For several months in early 1965 the sun appeared to have large scale magnetic field directed outwards at nearly all latitudes and longitudes. Several independent observations that lead to this puzzling situation are discussed.

Wilcox, J. M.↗
NASA NTRS1972

Ultraviolet photometry of the moon with the celescope experiment on the OAO-2

Thirteen television frames of the moon taken in the wavelength regions of 1350-2150 A by filter U sub 3 and 1050-2150 A by filter U sub 4 in the celescope experiment are discussed. The data include phase angles from -81 deg to -26 deg. The brightness dependence on phase angle differs slightly from that of visual observations. The brightness dependence on selenographical longitude is compared with the theoretical photometric function derived by Hapke.

Ahmad, I. A.↗
NASA NTRS1972

Variations of atmospheric density near 400 km with magnetic activity during the storm period of 28 September to 2 October 1969

Neutral density data were obtained near 400 km (1600 LT) from a microphone density gage on OGO-6 from 0 to 40 deg N geomagnetic latitude for 25 September through 3 October 1969. Several geomagnetic storms occurred during this period. Least squares fits were made to data points on density scatter diagrams. An equation representing the least squares fit was computed for each delay time. The equation of best fit (and the corresponding time delay between the density and the magnetic index which resulted in this best fit) was found by choosing the equation that gave the minimum standard error. The implications of the time differences associated with the best fits at various latitudes and longitudes are discussed with regard to the time delays involved in geomagnetic heating of the neutral upper atmosphere.

Anderson, A. D.↗
NASA NTRS1972

The application of color display techniques for the analysis of Nimbus infrared radiation data

A color enhancement system designed for the Applications Technology Satellite (ATS) spin scan experiment has been adapted for the analysis of Nimbus infrared radiation measurements. For a given scene recorded on magnetic tape by the Nimbus scanning radiometers, a virtually unlimited number of color images can be produced at the ATS Operations Control Center from a color selector paper tape input. Linear image interpolation has produced radiation analyses in which each brightness-color interval has a smooth boundary without any mosaic effects. An annotated latitude-longitude gridding program makes it possible to precisely locate geophysical parameters, which permits accurate interpretation of pertinent meteorological, geological, hydrological, and oceanographic features.

Allison, L. J.↗
NASA NTRS1972

Transport of cosmic rays in the solar corona

A method by which energetic cosmic ray particles in the interplanetary medium can diffuse in solar longitude. The method consists of particle motion occurring along current sheets separating discontinuous field structures in the corona. These sheets can serve as pathways along which energetic particles drift at nearly their propagation speed. A model of the coronal magnetic field and the large scale field behavior are analyzed. A mechanism by which particles can travel across the coronal magnetic field and arrive at the earth is suggested.

Schatten, K. H.↗
NASA NTRS1971

Cosmic-ray variations and the interplanetary sector structures.

Fifteen passages of interplanetary sector structures that occurred between December 1967 and June 1968 are examined. A spherical harmonic analysis of cosmic ray intensity is performed to obtain cosmic ray intensity variations as a function of asymptotic latitude, longitude, and universal time. A clear north-south asymmetry of cosmic ray intensity, which depends on the sign of the interplanetary sector magnetic fields, is revealed.

Yoshida, S.↗
NASA NTRS1971

100-micron survey of the galactic plane.

A survey of a portion of the galactic plane has been carried out at a wavelength of 100 micron with a beamwidth of 12 min. The survey covers 750 square degrees of the sky including most of the galactic plane between 335 and 88 deg galactic longitude and a number of other selected areas of interest. Seventy-two sources have been detected, 60 of which are identified with continuum radio sources, bright nebulae, dark nebulae, and infrared stars.

Hoffmann, W. F.↗
NASA NTRS1971

Martian craters and a scarp as seen by radar.

Radar observations of Mars with a surface resolution of 1.3 deg in latitude and 0.8 deg in longitude have been carried out during the opposition of 1971. With a precision in surface height measurement approaching 75 meters in regions of high reflectivity, it has been possible to measure the detailed characteristics of a number of craters. Many of these can be identified with craters shown in Mariner photographs of Mars. In addition, a scarp has been seen at 41 deg west, 14 deg south with an average slope of about 6 deg extending over about 40 kilometers.

Pettengill, G. H.↗
NASA NTRS1971

Mars radar observations - A preliminary report.

Radar observations of a narrow belt of the surface of Mars, centered at 16 deg south latitude, show a very rugged terrain, with elevation differences greater than 13 kilometers from peak to valley. For nearby points, the relative altitude is measured to 40 meters at best; the precision is worse for points at different latitudes, or widely separated in longitude, because of orbital uncertainties. Some of the larger craters have been resolved, and their depth and, in some cases, the height of the raised rim have been measured. Where high resolution photographs are available, the correlation is excellent.

Downs, G. S.↗
NASA NTRS1972

Lunar gravity via Apollo 14 Doppler radio tracking.

Gravity measurements at high resolution were obtained over a 100-kilometer band from +70 to -70 deg of longitude during the orbits of low periapsis altitude (approximately 16 kilometers). The line-of-sight accelerations are plotted on Aeronautical Chart and Information Center mercator charts (scale 1:1,000,000) as contours at 10-milligal intervals. Direct correlations between gravity variations and surface features are easily determined. Theophilus, Hipparchus, and Ptolemaeus are negative features, whereas Mare Nectaris is a large positive region. The acceleration profiles over Mare Nectaris are suggestive of a broad disk near the surface rather than a deeply buried spherical body.

Sjogren, W. L.↗
NASA NTRS1972

Pulsar rotation and dispersion measures and the galactic magnetic field.

Use of observations of pulsar polarization and pulse time of arrival at frequencies between 250 and 500 MHz to determine rotation and dispersion measures for 19 and 21 pulsars, respectively. These measurements have been used to calculate mean line-of-sight components of the magnetic field in the path to the pulsars. These and other observations show that there is probably no contribution to the observed rotation measure from the pulsar itself. Low-latitude, low-dispersion pulsars are observed to have strong field components, and a strong dependence of rotation-measure sign on galactic longitude has been found. The observations are consistent with a relatively uniform field of about 3.5 microgauss directed toward about l = 90 deg in the local region, but appear to be inconsistent with the helical model for the local field.

Manchester, R. N.↗
NASA NTRS1972

Venus - Topography revealed by radar data.

Surface height variations over the entire equatorial region on Venus have been estimated from extended series of measurements of interplanetary radar echo delays. Most notable is a mountainous section of about 3-kilometer peak height located at a longitude of 100 degrees (International Astronomical Union coordinate system). The eastern edge has an average inclination of about 0.5 degrees, which is unusually steep for a large-scale slope on Venus. The resolution of the radar measurements along the surface of Venus varied between about 200 and 400 kilometers with a repeatability in altitude determination generally between 200 and 500 meters. The mean equatorial radius was found to be 6050.0 plus or minus 0.5 kilometers.

Campbell, D. B.↗