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Chandra X-ray Observatory

Full resolution image

Credit: NASA

NASA's Advanced X-ray Astrophysics Facility, (AXAF), renamed the Chandra X-ray Observatory in honor of Subrahmanyan Chandrasekhar, was launched and deployed by the Space Shuttle Columbia on the 23 of July 1999. The combination of high resolution, large collecting area, and sensitivity to higher energy X-rays will make it possible for Chandra to study extremely faint sources, sometimes strongly absorbed, in crowded fields. Chandra was boosted into an elliptical high-earth orbit that allows long-duration uninterrupted exposures of celestial objects.

Mission Characteristics

* Lifetime: 23 July 1999 - (nominal 5 year mission)
* Energy Range: 0.1-10 keV
* Special Features: 64 Hours highly-eccentric Earth orbit.
Spatial resolution < 1 arcsec
* Payload:
A single Wolter Type 1 grazing incidence iridium-coated imaging telescope with a ghost free FOV ~ 30´ diameter and an effective area of 800 and 400 cm2 @ 0.25 and 5 keV respectively.
Four detectors could be inserted, one at a time, into the focal plane. Two of these were designed to be used primarily with the gratings.
  • AXAF Charged Coupled Imaging Spectrometer
    (ACIS; 0.2-10 keV) 2 CCD arrays for a total of 10 chips. 8 chips are Front Illuminated (FI) and 2 are Back Illuminated (BI).
    FI: Eff area 340 cm2 @ 1 keV, E/dE = 20-50 @ 1 and 6 keV
    BI: Eff area 340 cm<2 @ 1 keV, E/dE = 9-35 @ 1 and 6 keV
    • ACIS-I. One 4-chip imaging array, all FI. FOV 16´ X 16´
    • ACIS-S. One 6-chip spectroscopic array, 4 FI and 2 BI FOV 8´ X 48´. To be used primarily with the grating.
  • High Resolution Camera (HRC; 0.1-10 keV)
    2 micro-channel plate detectors.
    • HRC-I One 90mm square detector optimized for imaging. FOV ~30´ X 30´, eff. area 225 cm2 @ 1 keV, ~ 0.5 arcsec spatial resolution
    • HRC-S One 20 X 300 mm rectangular detector optimized for use with the LETG transmission gratings experiment. FOV 7´ X 97´
  • High Energy Transmission Grating + ACIS-S (HETG; 0.5-10 keV)
    spectral resolving power (E/dE) 60-1000.
  • Low Energy Transmission Grating + HRC-S (LETG; 0.08-6 keV)
    spectral resolving power (E/dE) 30-2000.

[Chandra Science Center] ( [Chandra User Support] (

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