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Low-/High-Resolution, Ultraviolet Spectrograph Package

NSSDCA ID: 1978-012A-01

Mission Name: IUE
Principal Investigator:Dr. Yoji Kondo


This experiment included the ultraviolet spectrograph package carried by the IUE, consisting of two physically distinct echelle-spectrograph/camera units capable of astronomical observations. Each spectrograph was a three-element echelle system composed of an off-axis paraboloidal collimator, an echelle grating, and a spherical first-order grating that was used to separate the echelle orders and focus the spectral display on an image converter plus SEC Vidicon camera. There was a spare camera for each unit. The camera units were able to integrate the signal. The readout/preparation cycle for the cameras took approximately 20 min. Wavelength calibration was provided by the use of a hollow cathode comparison lamp. The photometric calibration was accomplished by observing standard stars whose spectral fluxes had previously been calibrated by other means. Both echelle-spectrograph/camera units were capable of high-resolution (0.1 A) or low-resolution (6 A) performance. The dual high/low-resolution capability was implemented by the insertion of a flat mirror in front of the echelle grating, so that the only dispersion was provided by the spherical grating. As the SEC Vidicons could integrate the signal for up to many hours, data with a signal-to-noise ratio of 50 could be obtained for B0 stars of 9th and 14th magnitudes in the high- and low-resolution modes, respectively. The distinguishing characteristic of the units was their wavelength coverage. One unit covered the wavelength range from 1192 to 1924 A in the high-resolution mode and 1135 to 2085 A in the low-resolution mode. For the other unit, the ranges were from 1893 to 3031 A and 1800 to 3255 A for the high-and low-resolution modes, respectively. Each unit also had its own choice of entrance apertures: either a 3-arc-s hole or a 10- by 20-arc-s slot. The 10- by 20-arc-s slots could be blocked by a common shutter, but the 3-arc-s aperture was always open. As a result, two aperture configurations were possible: (1) both 3-arc-s apertures open and both 10- by 20-arc-s slots closed, or (2) all four apertures open. With this instrumentation, the observational options open to an observer were long-wavelength and/or short-wavelength spectrograph, high or low resolution, and large or small apertures. Exposures could be made with the two spectrographs simultaneously, but the entrance apertures for each were distinct and separated in the sky by about 1 arc-min. An additional restriction was that data could be read out from only one camera at a time. However, one camera could be exposed while the other camera was being read out. The choice of high or low resolution could be made independently for the two spectrographs. Listings of guest observers and their investigations can be obtained from the IUE Newsletter, IUE Observatory, Code 685, Goddard Space Flight Center, Greenbelt, Maryland 20771, U.S.A.

Alternate Names

  • IUE/Low-/High-Resolution,UltravioletSpectrographPackage
  • urn:esa:psa:context:instrument:iue.lwp
  • urn:esa:psa:context:instrument:iue.lwr
  • urn:esa:psa:context:instrument:iue.swp

Facts in Brief

Mass: 107 kg
Power (avg): 185 W
Bit rate (avg): 20 kbps

Funding Agencies

  • European Space Agency (International)
  • NASA-Office of Space Science (United States)
  • Science and Engineering Research Council, UK (United Kingdom)


  • Planetary Science: Fields and Particles
  • Astronomy: Ultraviolet

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Yoji KondoGeneral ContactNASA Goddard Space Flight Center
Dr. Yoji KondoLead InvestigatorNASA Goddard Space Flight Center

Selected References

  • Boggess, A., et al., The IUE spacecraft and instrumentation, Nature, 275, No. 5679, 372-376, doi:10.1038/275372a0, Oct. 1978.
  • Boggess, A., et al., In-flight performance of the IUE, Nature, 275, No. 5, 377-385, doi:10.1038/275377a0, Oct. 1978.
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