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NASA NTRS1982

Helios zodiacal light measurements - A tabulated summary

The intensity, color, and polarization of the average zodiacal light as observed by the Helios zodiacal light experiment between December 1974 and January 1981 are given in tabulated form. The tables give zodiacal light at 1 AU and 0.03 AU. The estimates of accuracy given here reflect possible systematic errors in the data. It is noted that repeatability from orbit to orbit and the smoothness of the plots against time or elongation are considerably better.

Leinert, C.↗
NASA NTRS1978

Zodiacal light as an indicator of interplanetary dust

The most striking feature of the night sky in the tropics is the zodiacal light, which appears as a cone in the west after sunset and in the east before sunrise. It is caused by sunlight scattered or absorbed by particles in the interplanetary medium. The zodiacal light is the only source of information about the integrated properties of the whole ensemble of interplanetary dust. The brightness and polarization in different directions and at different colors can provide information on the optical properties and spatial distribution of the scattering particles. The zodiacal light arises from two independent physical processes related to the scattering of solar continuum radiation by interplanetary dust and to thermal emission which arises from solar radiation that is absorbed by interplanetary dust and reemitted mainly at infrared wavelengths. Attention is given to observational parameters of zodiacal light, the methods of observation, errors and absolute calibration, and the observed characteristics of zodiacal light.

Weinberg, J. L.↗
NASA NTRS2001

Mapping the Inner Zodiacal Light with Clementine

Images of the inner zodiacal light were acquired by the Clementine spacecraft while orbiting the Moon in 1994. An all-sky map of the inner zodiacal light is obtained, and the distribution of dust throughout the inner solar system will also be reported. Additional information is contained in the original extended abstract.

Hahn, J. M.↗
NASA NTRS1982

Galactic and zodiacal light surface brightness measurements with the Atmosphere Explorer satellites

Galactic and zodiacal light surface maps based on the Atmosphere Explorer-C, -D, and -E satellite data are presented at 7320, 6300, 5577, 5200, and 4278 A. A procedure used to generate these maps, which involves separation of the individual stars and diffuse starlight from the zodiacal light, is described in detail. The maps can be used in atmospheric emission studies to correct for galactic emissions which contaminate satellite as well as ground-based photometric observations. The zodiacal light maps show enhanced features which are important for understanding the nature of interplanetary dust.

Abreu, V. J.↗
NASA NTRS1976

Space observations of the zodiacal light

An annotated tabular listing of balloon, rocket, satellite and space probe observations of zodiacal light from 1962 to 1974 is presented. Some selected results concerning zodiacal light observations from Skylab and Pioneers 10 and 11 are discussed, and some remarks on wavelength and spatial coverage of zodiacal light observations are made, noting the paucity of space observations in the ultraviolet and near the sun.

Weinberg, J. L.↗
NASA NTRS1977

On the photometric axis of the zodiacal light

A model of the zodiacal cloud is used to predict the position of the photometric axis (the locus of points of maximum brightness) of the zodiacal light at any elongation angle from the sun for any time of the year for various symmetry planes: the orbital planes of Venus, Mars, and Jupiter, the invariable plane, and the solar equatorial plane. Using a scattering function which combines isotropic scattering and Fresnel reflection, the geocentric distance of the dust that contributes most of the brightness at each elongation angle is determined by computing the brightness contribution along the line of sight. A comparison of the predicted and observed positions shows that at elongation angles of 15 to 60 deg, the axis of symmetry appears to be close to the orbital plane of Venus. At angles of less than 10 deg, it is difficult to distinguish among the proposed planes of symmetry. Observations of the photometric axis at angles of 60 to 180 deg are scarce and do not permit precise determination of the axis of symmetry in that region.

Misconi, N. Y.↗
NASA NTRS1985

Ground-based observations of near ecliptic zodiacal light brightness

Ground-based observation of the evening zodiacal light taken by Weinberg and Mann (1967) from Mt. Halaekala, Hawaii, during March 1966 are used to derive a table of zodiacal light brightnesses at high spatial resolution (as little as 0.5 deg in differential ecliptic longitude, DEL and 1.0 deg in ecliptic latitude beta) over the DEL region 29.5-56 deg, beta = -30 to +30 deg. Significant differences are found in the brightness distributions above and below the ecliptic plane.

Misconi, N. Y.↗
NASA NTRS2008

High Resolution Near Infrared Spectrometer to Study the Zodiacal Light Spectrum

We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 612, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I line at 5184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program.

Kutyrev, Alexander↗
NASA NTRS1976

Pioneer 10 observations of zodiacal light brightness near the ecliptic - Changes with heliocentric distance

Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees. The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background starlight brightnesses derived from IPP measurements beyond the asteroid belt, where the zodiacal light is not detected, and, especially, use of a corrected calibration lead to considerably lower values for zodiacal light than those reported by us previously.

Hanner, M. S.↗
NASA NTRS2008

High Efficiency Near Infrared Spectrometer for Zodiacal Light Spectral Study

We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 61 2, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I l~neat 5 184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program.

Kutyrea, A. S.↗
NASA NTRS1990

Small scale structure in the brightness of the zodiacal light - Ground-based observations

Ground-based observations of the evening zodiacal light are used to derive a table of zodiacal light brightnesses at spatial resolutions as small as 0.5 deg in differential ecliptic longitude and 1.0 deg in ecliptic latitude. Significant differences are found in the brightness distribution above and below the ecliptic plane. Attention is given to a feature found in the brightness at all ecliptic latitudes, between differential ecliptic longitudes 39 deg and 42 deg.

Misconi, Nebil Y.↗
NASA NTRS1972

The zodiacal light as seen from the Pioneer F/G and Helios probes.

During the years 1972-1976 the first deep-space observations of zodiacal light will be made: from the Pioneer F/G Asteroid-Jupiter probes and from the Helios solar probes which will penetrate to 0.25 AU. These vehicles provide a unique opportunity to determine the spatial distribution of interplanetary dust throughout the region from 0.1 to 5 AU and its concentration toward the ecliptic plane. Zodiacal light models are used to discuss the accuracy with which the spatial distribution of the interplanetary dust may be inferred from deep-space observations of zodiacal light, with special emphasis on the effects of a dust-free zone near the sun and of a particle concentration in the asteroid belt.

Hanner, M. S.↗