Wide Field Camera 3
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The Wide Field Camera 3 (WFC3) is the Hubble Space Telescope's last and most technologically advanced instrument to take images in the visible spectrum. It was installed as a replacement for the Wide Field and Planetary Camera 2 during the first spacewalk of Space Shuttle mission STS-125 on May 14, 2009.
The instrument is designed to be a versatile camera capable of imaging astronomical targets over a very wide wavelength range and with a large field of view. It is a fourth-generation instrument for Hubble. The instrument has two independent light paths: an optical channel that uses a pair of charge-coupled devices (CCD) to record images from 200 nm to 1000 nm; and a near infrared detector array that covers the wavelength range from 800 to 1700 nm. Both channels have a variety of broad and narrow-band filters, as well as prisms and grisms, which enable wide-field, very-low-resolution spectroscopy that is useful for surveys. The optical channel covers the visible spectrum (380 nm to 780 nm) with high efficiency, and is also able to see into the near ultraviolet (down to 200 nm).
Both detector focal planes were designed specifically for this camera. The optical channel covers a 164 by 164 arcsec (2.7 by 2.7 arcminute, about 8.5% of the diameter of the full moon as seen from Earth) field of view with 0.04 arcsec pixels. This field of view is comparable to the Wide Field and Planetary Camera 2 and is slightly smaller than the Advanced Camera for Surveys. The near infrared channel has a field of view of 135 by 127 arcsec (2.3 by 2.1 arcminutes) with 0.13 arcsec pixels, and has a much larger field of view than Near Infrared Camera and Multi-Object Spectrometer, which it is designed to largely replace. The near infrared channel is a pathfinder for the future James Webb Space Telescope. The IR channel is designed to lack sensitivity beyond 1700 nm (as compared with the 2500 nm limit for NICMOS) to avoid being swamped by thermal background coming from the relatively warm HST structure. This allows WFC3 to be cooled using a thermoelectric cooler instead of carrying a consumable cryogen to cool the instrument.
The camera makes use of returned space hardware as the structure is built from the original Wide Field and Planetary Camera as well as the filter assembly. These were switched for the Wide Field and Planetary Camera 2 by the servicing mission STS-61 in December 1993.
WFC3 was originally conceived as an optical channel only; the near infrared channel was added later. WFC3 is intended to ensure that Hubble retains a powerful imaging capability through to the end of its lifetime.
WFC3 had been in the planning since the Spring of 1998. It was built by a team of highly-experienced Hubble engineers and scientists drawn from many organizations, with leadership at Goddard Space Flight Center in Maryland. WFC3 was constructed mostly at Goddard Space Flight Center and Ball Aerospace in Colorado. Various parts were built by contractors across the United States and the United Kingdom.
The instrument was scheduled by NASA to launch with STS-125 on 14 October 2008, but the mission was postponed due to additional repairs that were required. The mission launched on 11 May 2009 and the WFC3 was installed on 14 May.
See also 
- Wide Field and Planetary Camera
- Wide Field and Planetary Camera 2
- Cosmic Origins Spectrograph
- Advanced Camera for Surveys
- Near Infrared Camera and Multi-Object Spectrometer
- Faint Object Camera
- MacKenty, J.W.; Kimble, R.A. (January 2003). Status of the HST Wide Field Camera 3 (pdf). American Astronomical Society poster session. p. 1.
- MacKenty 2003, p.4
- "Wide Field Camera 3 Fact Sheet". NASA. November 2007.
- MacKenty 2003, p.7
- "Space Telescope Operations Control Center — Flight Day 4". NASA. May 14, 2009.
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- The WFC3 Web site at the Space Telescope Science Institute, which includes a description of the instrument and a link that compares the capabilities of various Hubble instruments.
- Hubble Space Telescope Team
- Hubble instrument comparisons