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Goddard High-Resolution Spectrograph (GHRS)

NSSDCA ID: 1990-037B-02

Mission Name: HST
Principal Investigator:Dr. John C. Brandt, Jr.


This investigation uses an ultraviolet spectrograph capable of obtaining high-quality spectra at two resolving powers: 20,000 and 120,000. The lower dispersion is achieved with four gratings that cover the spectral range 1100 to 3200 A so that each grating is used only near its maximum blaze efficiency. The higher dispersion utilizes an echelle arrangement. The sensor is a multi-channel pulse-counting device, the digicon. This detector operates functionally like an image-dissector tube and can be used as an image dissector to perform star centering and field mapping of the entrance aperture, eliminating the need for a separate star tracker or slit camera. There are two detectors, one with a CsTe photocathode and one with CsI. The two target entrance apertures have fields of view of 1 sq arc-s and 0.3 sq arc-s, respectively. There are no significant time constraints. The high-resolution spectrograph (HRS) operates in sunlight so that it can be utilized at all times, except when the source is occulted by the earth or moon. The high dynamic range and choice of dispersions make it possible to observe a large range of stellar magnitudes, from very bright to moderately faint. The HRS bridges the gap between objects observed by rocket-borne spectrographs (Copernicus, IUE) and the faint-object spectrograph (FOS).

Alternate Names

  • GHRS
  • HRS
  • Scientific Instrument Package Unit No. 2 - High-Resolution Spectrograph

Facts in Brief

Mass: 318 kg
Power (avg): 150 W

Funding Agency

  • NASA-Office of Space Science United States


  • Astronomy: Ultraviolet

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Andrew M. SmithCo-InvestigatorNASA Goddard Space Flight Center
Dr. David S. LeckroneCo-InvestigatorNASA Goddard Space Flight
Dr. Sara R. HeapCo-InvestigatorNASA Goddard Space Flight
Dr. Albert BoggessCo-InvestigatorNASA Goddard Space Flight Center
Dr. Stephen P. MaranCo-InvestigatorNASA Goddard Space Flight
Dr. Laurence M. TraftonCo-InvestigatorUniversity of Texas,
Dr. John B. HutchingsCo-InvestigatorDominion Astrophysical
Dr. Jeffrey L. LinskyCo-InvestigatorUniversity of
Dr. Ray J. WeymannCo-InvestigatorUniversity of Arizona
Prof. Blair D. SavageCo-InvestigatorUniversity of
Dr. Edward A. BeaverCo-InvestigatorUniversity of California, San
Dr. Michael A. JuraCo-InvestigatorUniversity of California, Los
Dr. Dennis C. EbbetsCo-InvestigatorSpace Telescope Science Institute
Dr. C. Robert O'DellGeneral ContactNASA Marshall Space Flight
Dr. John C. Brandt, Jr.Principal InvestigatorUniversity of
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