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The SXG is a Russian-international observatory-class mission with participation from the US, UK, Italy, Germany, France, Denmark, Hungary, Switzerland, Finland, Turkey, and Israel. It will carry a complement of more than ten scientific instruments and detectors that span the electromagnetic spectrum from the extreme ultraviolet to gamma rays (0.06-100 MeV), with angular resolution from 10 arc-seconds to a few arc-degrees. The payload will consist of three grazing-incidence X-ray telescopes (SODART A and B, JET-X), a UV telescope (EUVITA), an X-ray telescope with coded-aperture instruments (MART), a Bragg spectrometer, two gaseous position-sensitive proportional counters (LEPC/HEPC), two solid-state Si(Li) detectors (SIXA), a gaseous scintillation proportional counter, X-ray CCD arrays, a stellar X-ray polarimeter (SXRP), an X-ray all-sky monitor (MOXE), and spectrometers for measuring gamma-ray bursts (DIOGENE and SPIN). The scientific objectives include high-resolution spectroscopy, timing observations, imaging of weak X-ray sources, determining X-ray source positions, monitoring transient events, investigating the origin of the diffuse X-ray background, and understanding the nature of gamma-ray bursts.

SXG will be in a highly elliptical, high-earth orbit. It will operate three out of four days. On the fourth day, there will be a reduction in observing time when the spacecraft traverses the Earth's magnetosphere. The SXG spacecraft consists of a main body and a pointing platform. The main body is triaxially stabilized to an accuracy of 2.5 arc-seconds. The spacecraft can be pointed to any direction in the sky, constrained only by the instruments' thermal control demands, detector solar illumination restrictions and telemetry requirements. The spacecraft pointing can be changed up to ten times per day via stored commands. Data stored on-board will be transmitted to the ground station once per day via a 2 Mbps telemetry link. A mission lifetime of at least three years is planned.

Alternate Names

  • SXG
  • Spectrum Roentgen Gamma
  • SRG

Facts in Brief

Launch Date: 2010-12-31
Launch Vehicle: Proton
Launch Site: Tyuratam (Baikonur Cosmodrome), Kazakhstan
Mass: 6000.0 kg

Funding Agencies

  • National Aeronautics and Space Administration (United States)
  • Institut Kosmicheskich Issledovaniy(Inst. of Cosmophysical Research) (Russia)


  • Astronomy

Additional Information

Questions or comments about this spacecraft can be directed to: Dr. Cynthia Y. Cheung.



NameRoleOriginal AffiliationE-mail
Dr. Frank J. GiovaneProject CoordinatorNASA
Prof. Rashid A. SunyaevProgram ManagerInstitut Kosmicheskich Issledovaniya (IKI) 
Dr. Guenter R. ReiglerProgram ManagerNASA
Dr. Herbert W. SchnopperProgram ManagerDanish Space Research Institute 
Dr. Alan N. BunnerProgram ScientistNASA Headquarters 

Other Sources of SXG Information/Data

U.S. Spectrum-X-Gamma Coordination Facility
Spectrum-X-Gamma Project page at IKI
Spectrum Roentgen Gamma Project page at DSRI

SODART X-ray telescope (IKI)
JET-X (U. of Leicester)
FUVIT - Far UV Imaging Telescope Array (Paul Scherrer Institute)
MOXE - Monitoring X-ray Experiment (LANL)
TAUVEX Ultraviolet Telescope (SAO)

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