Spitzer space telescope irac camera filters

The Infrared Array Camera (IRAC) was an

infrared camera Infrared thermography (IRT), thermal video or thermal imaging, is a process where a thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are examples of infrared im ...

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, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

'' which operated in the

mid-infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those of ...

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

s of sky with each pixel covering 1.2

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

. 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 sy ...

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

silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

doped with

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

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

beryllium Beryllium is a chemical element; it has Symbol (chemistry), symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with ...

. 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 less customized than specially-produced satelli ...

. 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 ...

and the detectors were built by

Raytheon Raytheon is a business unit of RTX Corporation and is a major U.S. defense contractor and industrial corporation with manufacturing concentrations in weapons and military and commercial electronics. Founded in 1922, it merged in 2020 with Unite ...

. 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 Astrophysics, astrophysical studies including Galactic astronomy, galactic and extragalactic astronomy, cosmology, Sun, solar ...

Bands summary

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

micron The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

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), previously known as the Harvard–Smithsonian Center for Astrophysics, is an astrophysics research institute jointly operated by the Harvard College Observatory and Smithsonian Astrophy ...

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 T ...

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

Bands summary

See also

References

External links