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UV Airglow Spectrometer 1100-1750A, 1750-3400A

NSSDCA ID: 1967-073A-14

Mission Name: OGO 4
Principal Investigator:Dr. Charles A. Barth


An Ebert-Fastie scanning spectrometer was used to measure the ultraviolet (UV) spectrum of the earth in the wavelength range from 1100 to 3400 A, with a 20-A resolution. The objectives of this experiment ncluded the measurement of the intensity of the following emissions: (a) the hydrogen Lyman-alpha on both the day and night sides, (b) the atomic oxygen 1304-A day and twilight glow, and (c) the atomic oxygen 1356-A line, the atomic nitrogen 1493-A line, and the molecular nitrogen Lyman-Birge-Hopfield bands of the photoelectron excited dayglow. Another objective was the determination of the vertical distribution of ozone from the measurement of the back-scattered UV daylight in the 2000-to 3400-A range. The focal length of the Ebert mirror was 250 mm, and the grating used had 2160 lines per millimeter. The spectral scan period was essentially 74.5 s. However, during about 7% of the time, this scan period was reduced to 18.6 s. The instrument was mounted looking to nadir. The F channel was the output of a photomultiplier tube (PMT) with a sapphire window and a cesium telluride cathode. The wavelength interval measured here extended from 1750 to 3400 A, with a dynamic range of intensities of 1.E6. The G data channel was the output of a PMT with a lithium fluoride window and a cesium iodide cathode. On this channel the wavelength ranges scanned extended from 1100 to 1750 A, and the measured intensity could vary over a range from 1 to 1000. The exponential voltage gain characteristics of the PMT resulted in a near-logarithmic scaling between flux and high-voltage level. Appropriate circuitry translated the output to 1-to-5-V analog, an output signal consistent with the spacecraft data system. Prefocused light sources, some operated by command, provided in-orbit calibrations. A complete description of this experiment can be found in C. A. Barth and E. F. Mackey, "OGO-IV ultraviolet airglow spectrometer," IEEE Transactions on Geoscience Electronics, v. GE-7, n. 2, pp. 114-119, April 1969.

Alternate Names

  • OGO4/UVAirglowSpectrometer1100-1750A,1750-3400A

Facts in Brief

Mass: 11.3 kg
Power (avg): 13 W

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Space Physics: Ionospheric Studies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Lloyd J. WallaceOther InvestigatorKitt Peak National
Mr. E. F. MackeyOther InvestigatorPackard-Bell Corporation
Dr. Charles A. BarthPrincipal InvestigatorUniversity of
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