1. The Chandra X-Ray Observatory

2. History

3. The Chandra X-Ray Observatory: History
Spaced-based X-Ray Observatory
Proposed in 1976, funding began in 1977
Re-designed in 1992
Number of mirrors lowered from twelve to four
Instruments lowered from six to four
Orbit changed from LEO to HEO to compensate
Finally launched on July 23, 1999

4. The Chandra X-Ray Observatory: History
Both the heaviest and the largest satellite ever launched by a shuttle
Highly elliptical orbit, ranging from km out to km, with a period of 64h 18m
This is so it can avoid most of the charged particles within the Earth's atmosphere
Named after Subrahmanyan Chandrasekhar, who discovered the mass limit of white dwarfs
“Chandra” also means “moon” in Sanskrit

5. The Chandra X-Ray Observatory: History
Intended to expand the field of X-Ray astronomy
Earth-based telescopes are poor for detecting X- Rays, as the atmosphere absorbs most of them
Nearly 100x more sensitive to X-Ray sources than any previous X-Ray telescope
Its mission was planned to last five years
Has now lasted just over thirteen years, six months
Remains the “most powerful” X-Ray observatory ever built

6. The Chandra X-Ray Observatory: History
Image credit NASA/CSC/SAO, s/craftIllustrations.html

7. The Chandra X-Ray Observatory: History
Chandra X-Ray Center operated by the Smithsonian Astrophysical Observatory (SAO) in Cambridge, MA.
Personnel from SAO, MIT (created several instruments) and Northrop-Grumman (built the observatory)
Program managed by the NASA Marshall Space Flight Center
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8. The Chandra X-Ray Observatory: History
Anyone can book time on the telescope, provided a good (scientific) reason / target
Information about proposals can be found at
Proposals must be submitted electronically, either by or at

9. Design

10. The Chandra X-Ray Observatory: Design
As an X-Ray telescope, Chandra cannot use a conventional mirror alignment
Mirrors aligned nearly parallel to incoming X-Rays
Allows X-Rays to “glance” off the mirrors and be focused into a detector
Design based on the “Wolter” telescope design
The mirrors were ground to within a few atoms of perfect smoothness
The “smoothest and cleanest” mirrors ever made
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11. The Chandra X-Ray Observatory: Design
Mirrors were coated in iridium to aid in the reflection of the X-Rays
Mirror assembly is 2.7m long and is accurate to within 1.3 µm
Diameter of mirror assembly is 1.2 m
Focal length of 10 m
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12. The Chandra X-Ray Observatory: Design
Four scientific instruments on-board:
High Resolution Camera (HRC)
Advanced CCD Imaging Spectrometer (ACIS)
High Energy Transmission Grating Spectrometer (HETGS)
Low Energy Transmission Grating Spectrometer (LETGS)
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13. The Chandra X-Ray Observatory: Design
High Resolution Camera:
One of two instruments at the focal plane of the telescope
Can reveal detail as small as half an arcsecond
Image range between 0.1 – 10 keV
Best used for observing hot matter, distant galaxies and faint sources
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14. The Chandra X-Ray Observatory: Design
Advanced CCD Imaging Spectrometer:
Other of two instruments at the focal plane of the telescope
An array of 10 CCDs
Image range from 0.2 – 10 keV
Capable of measuring the energy of each incoming X-Ray
Can image an object using X-Rays from a single element
Best used for studying temperature or chemical variations in large gas clouds
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15. The Chandra X-Ray Observatory: Design
High Resolution Spectrometers:
Swung into place behind the mirrors when needed
Composed of hundreds of gold transmission gratings
Change the direction of the incoming X-Rays dependent on their energy
Allows precise calculation of the ray's energy
LETGS ranges from 0.08 – 2 keV
HETGS ranges from 0.4 – 10 keV
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16. The Chandra X-Ray Observatory: Design
The Spectrometers can be used in conjunction with the HRC or ACIS to create high-resolution spectral images
These devices work together to give the telescope a range of roughly 0.1 – 10 keV, or roughly 0.01 – 1 nm
Has an angular resolution of roughly 0.5 arcseconds
Field of View of about 30 x 30 arcminutes
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17. The Chandra X-Ray Observatory: Design
The Crab Nebula. Image credit NASA / ESA rabneb.html

18. The Chandra X-Ray Observatory: Design
Supernova 1987 A. Credit: X-ray: NASA/CXC/PSU/S.Park & D.Burrows.; Optical: NASA/STScI/CfA/P.Challis

19. Research

20. The Chandra X-Ray Observatory: Research
Being such a powerful telescope in the (relatively) new field of X-Ray astronomy, Chandra has aided in many discoveries
Most often used to examine supernova remnants
Neutron stars, pulsars, black holes and nebulae
ray_Observatory#Discoveries

21. The Chandra X-Ray Observatory: Research
Discoveries
First Light image was the first visual confirmation of a compact object at the center of SNR Cas A
Earliest images of the X-Ray shock-wave from SN1987A
First X-Ray images of Sgr A*
ray_Observatory#Discoveries

22. The Chandra X-Ray Observatory: Research
First ever images of the “shadow” of a galaxy
Perseus A is a large galaxy that has grown by consuming smaller galaxies
Caught in the act of devouring a smaller galaxy
X-Ray images from Chandra show the X-Ray shadow of the smaller galaxy as it's being pulled apart by Perseus A
Image taken on January 29, 2000
6.8 hr exposure using ACIS
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23. The Chandra X-Ray Observatory: Research
Perseus A. Credit:NASA/IoA/A.Fabian et al. index.html

24. The Chandra X-Ray Observatory: Research
Other possible discoveries include:
A “mid-mass” black hole in M82, thought to be the “missing link” between stellar-mass and supermassive black holes
Data from the observations of two stars, originally thought to be neutron stars, indicates that they may actually be “quark stars”
Results still up for debate
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25. The Chandra X-Ray Observatory: Research
Tycho Supernova Remnant. Credit NASA/CXC/Chinese Academy of Sciences/F. Lu et al

26. The Chandra X-Ray Observatory: Research
B1509 “The Hand of God”. Credit NASA/CXC/SAO/P.Slane, et al.