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Infrared Array Camera

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IRAC filters
Here is a four-band IRAC image. Because its near-to mid infrared, the wavelengths the cameera see's are mapped to the visible colors that humans see for an image (See False color). In this image of the Trifid nebula 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red).

Infrared Array Camera (IRAC) is an instrument on the Spitzer Space Telescope.[1] It is an electronic infrared camera for astronomical imaging, and it can detect from the near to mid infrared.[2] The sensor can detect light with a wavelength of 3 microns to 8 microns when chilled.[3] The detectors have a resolution of 256 by 256 pixels, and there is four detectors that view four bands at the same time.[4][5] Each detector has 65000 pixels, which was a big increase over previous infrared telescopes.[6] The IRAC detector takes in light from the telescopes reflecting optics, which consits of a primary and secondary mirror made of beryillium metal.[7]

Light bands IRAC can observe in wavelength microns:[8][9]

  • 3.6
  • 4.5
  • 5.8
  • 8.0

It can view all four wavelength bands at the same time, whats called a broad-band image.[10] The 3.6 and 4.5 micron bands use InSb (Indium antimonide) detectors, and the 5.8 and 8 micron bands use Si:As (Silicon doped with Arsenic) detecors[11][12][13] The 3.6 and 4.5 wavelengths band could be operated when the coolant runs out and the telescope warms up, whereas the 5.8 and 8 microns wavelength bands operated only when the coolant chilled the telescope to even colder temperatures.[14] The IRAC instrument is contained in the Spitzer Multiple Instrument Chamber with several other pieces of technology, including the other focal plane instruments.[15] In the MIC is the Infrared Array Camera, Infrared Spectrograph, and Multiband Imaging Photometer as well as the pointing calibration reference sensor.[16] The MIC is attached to the cryostat and it is intended to keep the science instruments cold, including IRAC, but also to keep stray light.[17] The IRAC, inside the MIC, is enlclosed with the outer shell of the spacecraft/observatory, which also has a thermal shield to help keep the telescope cool.[18] Like the rest of the Spitzer, IRAC was launched into space in 2003 into a Earth-trailing heliocentric orbit (it is orbiting the Sun not Earth).[19]

References

  1. ^ [1]
  2. ^ [2]
  3. ^ [3]
  4. ^ [4]
  5. ^ [5]
  6. ^ [6]
  7. ^ [7]
  8. ^ [8]
  9. ^ [9]
  10. ^ [10]
  11. ^ [11]
  12. ^ [12]
  13. ^ [13]
  14. ^ [14]
  15. ^ [15]
  16. ^ [16]
  17. ^ [17]
  18. ^ [18]
  19. ^ [19]

See also

  • NIRCam (planned JWST camera for 0.6 to 5 micron light)
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