Spitzer space telescope irac camera filters

The Infrared Array Camera (IRAC) was an

infrared camera Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

system on the ''

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...

'' which operated in the

mid-infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

spectrum. It was composed of four detectors that operated simultaneously at different wavelengths; all four were in use until 2009 May 15 when the ''Spitzer''

cryostat A cryostat (from ''cryo'' meaning cold and ''stat'' meaning stable) is a device used to maintain low cryogenic temperatures of samples or devices mounted within the cryostat. Low temperatures may be maintained within a cryostat by using various ...

ran out of liquid helium. After then, the spacecraft operated in a warm extended mission, in which two of the four detectors remained functional, until the ''Spitzer'' mission was terminated on 2020 January 30. During its primary mission, IRAC was able to simultaneously operate in four wavelengths: 3.6 μm, 4.5 μm, 5.8 μm, and 8.0 μm. Each infrared detector had dimensions of 256×256 pixels—a significant improvement over previous spaceborne infrared telescopes—and each image taken covered 5.12 square

arcminute A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

s of sky with each pixel covering 1.2

arcseconds A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

. The detectors operating at 3.6 μm and 4.5 μm were constructed with

indium antimonide Indium antimonide (InSb) is a crystalline compound made from the elements indium (In) and antimony (Sb). It is a narrow- gap semiconductor material from the III- V group used in infrared detectors, including thermal imaging cameras, FLIR systems ...

(InSb), while the 5.8 μm and 8.0 μm detectors were made of

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...

doped with

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but ...

(Si:As). The telescope's primary and secondary mirrors, along with its supporting structure, were made mostly of

beryllium Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form mi ...

. The telescope was cryogenically cooled to around ; the 3.6 μm and 4.5 μm detectors operated at and the 5.8 μm and 8.0 μm detectors operated at . After ''Spitzer'' liquid helium coolant ran out on 2009 May 15, the spacecraft warmed up over several months. IRAC stabilized at its warm mission operating temperature of on 2009 September 18. This meant that the 5.8 μm and 8.0 μm detectors could not function as they required the cryogenic cooling, but the 3.6 μm and 4.5 μm detectors remained about as sensitive as they were during the primary mission. The other two ''Spitzer'' instruments (IRS and MIPS) likewise ceased to function as they worked at longer wavelengths, leaving IRAC as the sole operational instrument. The cryogenic assembly of IRAC is contained in the ''Multiple Instrument Chamber'' (MIC), which also houses the other focal plane elements and the pointing calibration reference sensor. In the MIC is the ''Infrared Array Camera'', ''Infrared Spectrograph'', and ''Multiband Imaging Photometer'', as well as the pointing calibration reference sensor. The MIC is attached to the cryostat and was intended to keep the science instruments, including IRAC, cold but also functioned to keep out stray light. The MIC is mounted to the helium chamber inside the cryostat vacuum shell, not only to efficiently keep the instruments cold but to seal out any stray light. The IRAC warm electronics assembly is housed in the

spacecraft bus A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held. Bus-derived satellites are opposed to specially produced satellites. Bus-d ...

. The IRAC instrument was built by the

Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States. Established on May 1, 1959 as NASA's first space flight center, GSFC empl ...

and the detectors were built by

Raytheon Raytheon Technologies Corporation is an American multinational aerospace and defense conglomerate headquartered in Arlington, Virginia. It is one of the largest aerospace and defense manufacturers in the world by revenue and market capitaliza ...

. Its operational and scientific management is handled by the

Smithsonian Astrophysical Observatory The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution, concentrating on astrophysical studies including galactic and extragalactic astronomy, cosmology, solar, earth and planetary sciences, the ...

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IRAC was capable of observing in the wavelengths of 3.6, 4.5, 5.8, and 8.0

micron The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

s. When its coolant ran out, only the two shorter wavelengths remained usable.

References

External links

IRAC website
by the

Harvard–Smithsonian Center for Astrophysics The Center for Astrophysics , Harvard & Smithsonian (CfA), alternatively called the Harvard–Smithsonian Center for Astrophysics, is an astrophysics research institute jointly operated by the Harvard College Observatory and Smithsonian Astrop ...

Spitzer Documentation & Tools: IRAC
by the

Infrared Science Archive The Infrared Science Archive (IRSA) is the primary archive for the infrared and submillimeter astronomical projects of NASA, the space agency of the United States. IRSA curates the science products of over 15 missions, including the Spitzer Space ...

{{Use dmy dates, date=January 2017 Spitzer Space Telescope Astronomy image sensors

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See also

References

External links