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Gegenschein Photometry

NSSDCA ID: 1964-054A-11

Mission Name: OGO 1
Principal Investigator:Dr. Charles L. Wolff

Description

This experiment was designed to measure the amount of solar light that is scattered by particles in space (dust, etc.) in the neighborhood of the anti-solar point. This light contribution to the night sky is called the gegenschein. The basic data from this experiment were to be pictures of the sky at the antisolar point taken by a TV camera and telemetered to earth as a 22 x 32 matrix. The experimental package was a photoelectric camera which formed images of the sky in the visible and near-visible light. The data from this assembly were transmitted back to earth, where they were reconstructed into pictures. Each of these pictures covered about 100 square degrees of sky with a resolution of 0.5 degrees. The package consisted of (1) a four-element f/1.5 objective lens, (2) a filter wheel containing five filters that covered the range from 3000 to 7000 A, (3) an S-20 cathode deposited on a thin, curved window of Corning 9741 ultraviolet-transmitting glass, (4) an image dissector tube named the Star Tracker FW 143B made by the ITT Corporation, and (5) an electronic unit that amplified and counted the current pulses coming from the tube due to the individual photons arriving at the photocathode. The system was designed to operate at low light levels. Its overall quantum efficiency was of the order of 5%. Unfortunately, upon attaining orbit OGO 1 went into an uncontrolled spin, and the experiment failed to achieve its experimental objective. In addition, after three months in orbit the filter wheel refused to rotate due to an electrical failure in the wheel drive circuit. Despite the failure to achieve the initial goals of the experiment, an interesting study was made determining the effects of the Van Allen belt particle fluxes on the scientific package. These results were published by C. L. Wolff in Applied Optics, v. 5, n. 11, p. 1838, 1966. Data from this investigation no longer exist.

Alternate Names

  • OGO1/GegenscheinPhotometry

Funding Agency

  • National Aeronautics and Space Administration (United States)

Disciplines

  • Space Physics: Zodiacal Light/Interplanet Dust
  • Planetary Science: Small Bodies

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Kenneth L. HallamOther InvestigatorNASA Goddard Space Flight Center
Mr. S. P. WyattOther InvestigatorUniversity of Illinois
Dr. Charles L. WolffPrincipal InvestigatorNASA Goddard Space Flight CenterCharles.Wolff@nasa.gov
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