Wide Field and Planetary Camera 2

The Wide Field and Planetary Camera 2 (WFPC2) is a camera formerly installed on the Hubble Space Telescope. The camera was built by the Jet Propulsion Laboratory and is roughly the size of a baby grand piano. It was installed by servicing mission 1 (STS-61) in 1993, replacing the telescope's original Wide Field and Planetary Camera (WF/PC). WFPC2 was used to image the Hubble Deep Field in 1995, the Hourglass Nebula and Egg Nebula in 1996, and the Hubble Deep Field South in 1998. During STS-125, WFPC2 was removed and replaced with the Wide Field Camera 3 as part of the mission's first spacewalk on May 14, 2009. After returning to Earth, the camera was displayed briefly at the National Air and Space Museum and the Jet Propulsion Laboratory before returning to its final home at the Smithsonian's National Air and Space Museum.[1][2]

Wfpc20101013r
Brought back to Earth by the U.S. Space Shuttle, the WFPC is loaded for transport after display at JPL on its way to its final home at the National Air and Space Museum in 2010
Quantum efficiency graph for WFPC2-en
Quantum efficiency of the CCD chip in the camera

Design

WFPC2 was built by NASA's Jet Propulsion Laboratory, which also built the predecessor WF/PC camera launched with Hubble in 1990. WFPC2 contains internal corrective optics to fix the spherical aberration in the Hubble telescope's primary mirror.

The charge-coupled devices (CCDs) in the WFPC2 (designed at JPL and manufactured by Loral) detected electromagnetic radiation in a range from 120 nm to 1000 nm. This included the 380 nm to 780 nm of the visible spectrum, all of the near ultraviolet (and a small part of the extreme ultraviolet band) and most of the near infrared band. The sensitivity distribution of these CCDs is roughly normal, with a peak around 700 nm and concomitantly very poor sensitivity at the extremes of the CCDs' operating range. WFPC2 featured four identical CCD detectors, each 800x800 pixels. Three of these, arranged in an L-formation, comprise Hubble's Wide Field Camera (WFC). Adjacent to them is the Planetary Camera (PC), a fourth CCD with different (narrower-focused) optics. This afforded a more detailed view over a smaller region of the visual field. WFC and PC images are typically combined, producing the WFPC2's characteristic stairstep image. When distributed as non-scientific JPEG files the PC portion of the image is shown with the same resolution as the WFC portions, but astronomers receive a raw scientific image package which presents the PC image in its native, higher detail.

To allow scientists to view specific parts of the electromagnetic spectrum the WFPC2 featured a rotating wheel which moves different optical filters into the lightpath (between the WFPC2's aperture and the CCD detectors). The 48 filter elements included:

  • A set of standard wideband photometric filters.
  • A graduated filter, featuring a wide range of very narrowband filters. By positioning the target object at a precise part of the field, the operator can use an accurately picked narrowband filter.
  • A number of narrowband optical filters tuned to the wavelengths of various atomic emission lines.

Performance

Small Section of the Carina Nebula
Picture of small section of the Carina Nebula created from images taken with Hubble's Wide Field Planetary Camera 2.[3]

As predicted, over the course of its mission the WFPC2 experienced degradation of the CCDs, resulting in defective ("hot") pixels. The telescope's operators perform monthly calibration tests to catalog these; with the WFPC's aperture closed a number of long exposures are taken, and pixels which differ significantly from near black are flagged. To avoid false positives caused by cosmic rays tripping a given pixel, the output of different calibration shots are compared. Pixels which are consistently "hot" are recorded, and astronomers who analyse raw WFPC2 images receive a list of these pixels. Typically astronomers adjust their photo-processing software to ignore these bad pixels.

WFPC2 was largely superseded for broad-band imaging by the Advanced Camera for Surveys, installed during servicing mission 3B in 2002. However, the early 2007 failure of ACS resulted in WFPC2 returning to its role as Hubble's primary visible light camera. WFPC2 was removed from HST during Servicing Mission 4 in May 2009, for return to Earth and eventual museum display. It was replaced by Wide Field Camera 3, which features two UV/visible detecting CCDs, each 2048x4096 pixels, and a separate IR CCD of 1024 x 1024, capable of receiving infrared radiation up to 1700 nm.

See also

WFPC2 images

Jfader hubble

Hubble Space Telescope WFPC2 image of the Hubble Deep Field showing the characteristic stairstep composition of WFPC2 images

1994-02-b-full jpg

WFPC 2 image in 1994 of M100 (NGC 4321)

STSci-PRC01-33 omega centauri

Part of Omega Centauri

References

  1. ^ ""The Camera that Saved Hubble" Coming to the Smithsonian". May 27, 2009. Retrieved July 14, 2009.
  2. ^ "The Camera That Saved Hubble Leaves the Nest". JPL / NASA. Retrieved October 14, 2010.
  3. ^ "Return to the Carina Nebula". ESA/Hubble Picture of the Week. ESA/Hubble. Retrieved July 4, 2011.

External links

Apparition (EP)

Apparition is the second EP by the progressive metal band, The Contortionist. It was self-released by the band on September 24, 2009. The release shows the band's first move towards a more technical death metal sound while their debut EP, Shapeshifter, showed a more traditional deathcore sound. It is also the last release with Dave Hoffman on vocals, with Jonathan Carpenter joining afterwards to fill in the spot. Not long after the release of this EP, the band was signed to Good Fight and released their debut album, Exoplanet in the following year. The EP's artwork is a Hubble Space Telescope mosaic image assembled from 24 individual Wide Field and Planetary Camera 2 exposures taken in October 1999, January 2000, and December 2000 of the Crab Nebula.

Most of the tracks were remastered and got new lyrics in the album Exoplanet:

“Infection" was changed into “Expire", “Realms" became “Advent, “Eyes: Closed" became “Flourish" and of course, “Oscillator" had its redux with the same title.

There was also a Demo of “Predator" called “Predator Posing As A House Pet", which was released in the MySpace account of the band during the release of the Shapeshifter EP, but wasn't released as an album track of it.

Association (astronomy)

An association (astronomy) is a combined or co-added group of astronomical exposures from which cosmic rays have been removed. WFPC2 associations constitute one type of association and are tools in the Hubble Space Telescope (HST) archive for using data from the Wide Field and Planetary Camera 2 (WFPC2). Associations were introduced in the HST archive at the beginning of 1998. Since then, astronomers have been able to retrieve on-the-fly re-calibrated co-added WFPC2 images that have already been cleaned of cosmic rays from the Space Telescope European Coordinating Facility (ST-ECF), the Canadian Astronomy Data Centre (CADC) and Space Telescope Science Institute (STScI) archives.

Egg Nebula

The Egg Nebula (also known as RAFGL 2688 and CRL 2688) is a bipolar protoplanetary nebula approximately 3,000 light-years away from Earth. Its peculiar properties were first described in 1975 using data from the 11 µm survey obtained with sounding rocket by Air Force Geophysical Laboratory (AFGL) in 1971 to 1974. (Previously, the object was catalogued by Fritz Zwicky as a pair of galaxies.)

The Egg Nebula's defining feature is the series of bright arcs and circles surrounding the central star. A dense layer of gas and dusts enshrouds the central star, blocking its direct light from our view. However, the light from the central star penetrates the thinner regions of this dusty enclosure, illuminating the outer layers of gas to create the arcs seen in this resplendent image (Hubble Site).

The dusty enclosure around the central star is very likely a disc. The bipolar outflows in the image indicate that the system has angular momentum, which is very likely generated by an accretion disc. In addition, a disc geometry would account for the varying thickness of the enclosure that allows light to escape along the disc's axis and illuminate the outer layers of gas, but still blocks it from our direct view along the disc edge. Although dusty discs have been confirmed around several post-AGB objects (S. De Ruyter et al., 2006), a disc around the Egg Nebula is yet to be confirmed.

The Egg Nebula was photographed by the Wide Field and Planetary Camera 2 of the NASA/ESA Hubble Space Telescope.

The Egg Nebula emits polarized light which can also be detected visually by a medium-sized telescope.

Engraved Hourglass Nebula

The Engraved Hourglass Nebula (also known as MyCn 18) is a young planetary nebula in the southern constellation Musca. It was discovered by Annie Jump Cannon and Margaret W. Mayall during their work on an extended Henry Draper Catalogue (the catalogue was built between 1918 and 1924). At the time, it was designated simply as a small faint planetary nebula. Much improved telescopes and imaging techniques allowed the hourglass shape of the nebula to be discovered by Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory on January 18, 1996. It is conjectured that MyCn 18's hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles. The vivid colours given off by the nebula are the result of different 'shells' of elements being expelled from the dying star, in this case helium, nitrogen, oxygen and carbon.

The Hourglass Nebula was photographed by the Wide Field and Planetary Camera 2 of the Hubble Space Telescope.

A less-famous "Hourglass Nebula" is located inside the Lagoon Nebula.

Hubble (film)

Hubble (also known as Hubble 3D, IMAX: Hubble, or IMAX: Hubble 3D) is a 2010 American documentary film about Space Shuttle missions to repair and upgrade the Hubble Space Telescope. It is narrated by the actor Leonardo DiCaprio.

Hubble Deep Field

The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2.6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and December 28, 1995.The field is so small that only a few foreground stars in the Milky Way lie within it; thus, almost all of the 3,000 objects in the image are galaxies, some of which are among the youngest and most distant known. By revealing such large numbers of very young galaxies, the HDF has become a landmark image in the study of the early universe.

Three years after the HDF observations were taken, a region in the south celestial hemisphere was imaged in a similar way and named the Hubble Deep Field South. The similarities between the two regions strengthened the belief that the universe is uniform over large scales and that the Earth occupies a typical region in the Universe (the cosmological principle). A wider but shallower survey was also made as part of the Great Observatories Origins Deep Survey. In 2004 a deeper image, known as the Hubble Ultra-Deep Field (HUDF), was constructed from a few months of light exposure. The HUDF image was at the time the most sensitive astronomical image ever made at visible wavelengths, and it remained so until the Hubble eXtreme Deep Field (XDF) was released in 2012.

Hubble Deep Field South

The Hubble Deep Field South is a composite of several hundred individual images taken using the Hubble Space Telescope's Wide Field and Planetary Camera 2 over 10 days in September and October 1998. It followed the great success of the original Hubble Deep Field in facilitating the study of extremely distant galaxies in early stages of their evolution. While the WFPC2 took very deep optical images, nearby fields were simultaneously imaged by the Space Telescope Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS).

Lucy–Hook coaddition method

The Lucy–Hook coaddition method is an image processing technique for combining sub-stepped astronomical image data onto a finer grid. The method allows the option of resolution and contrast enhancement or the choice of a conservative, re-convolved, output.Tests with very deep Hubble Space Telescope Wide Field and Planetary Camera 2 (WFPC2) imaging data of excellent quality show that these methods can be very effective and allow fine-scale features to be studied better than on the unprocessed images. The Lucy–Hook coaddition method is an extension of the standard Richardson–Lucy deconvolution iterative restoration method.

For many purposes it may be more convenient to combine dithered datasets using the Drizzle method.

Mystic Mountain

Mystic Mountain is a photograph and a term for a region in the Carina Nebula imaged by the Hubble Space Telescope. The view was captured by the then-new Wide Field Camera 3, though the region was also viewed by the previous generation instrument. The new view celebrated the telescope's 20th anniversary of being in space in 2010. Mystic Mountain contains multiple Herbig-Haro objects where nascent stars are firing off jets of gas which interact with surrounding clouds of gas and dust.This region is about 7,500 light-years (2,300 pc) away from Earth. The pillar measures around three light-years in height (190,000 astronomical units).

NGC 3198

NGC 3198, also known as Herschel 146 is a barred spiral galaxy in the constellation Ursa Major. It was discovered by William Parsons, 3rd Earl of Rosse (Lord Rosse), sometime before 1850.NGC 3198 is located in the Leo Spur, which is part of the Virgo Supercluster, and is approximately 47 million light years away.

NGC 428

NGC 428 is a barred spiral galaxy in the constellation of Cetus (The Sea Monster), with its spiral structure distorted and warped, possibly the result of the collision of two galaxies. There appears to be a substantial amount of star formation occurring within NGC 428 and lacks well defined arms — a telltale sign of a galaxy merger. In 2015 the Hubble Space Telescope made a close-up shot of the galaxy with its Advanced Camera for Surveys and its Wide Field and Planetary Camera 2. The structure of NGC 428 has been compared to NGC 5645.

NGC 4634

NGC 4634 is an edge-on barred spiral galaxy located about 70 million light-years away in the constellation of Coma Berenices. NGC 4634 was discovered by astronomer William Herschel on January 14, 1787. It is interacting with the spiral galaxy NGC 4633. Both galaxies are members of the Virgo Cluster.

NGC 7026

NGC 7026 is a planetary nebula located 6000 light years away, in the constellation of Cygnus. This image was produced by the Hubble Space Telescope using the Wide Field and Planetary Camera 2 aboard.

On-The-Fly Calibration

In observational astronomy an On-The-Fly Calibration (OTFC) system calibrates data when a user's request for the data is processed so that users can obtain data that are calibrated with up-to-date calibration files, parameters, and software.

Pillars of Creation

Pillars of Creation is a photograph taken by the Hubble Space Telescope of elephant trunks of interstellar gas and dust in the Eagle Nebula, specifically the Serpens constellation, some 6,500–7,000 light years from Earth. They are so named because the gas and dust are in the process of creating new stars, while also being eroded by the light from nearby stars that have recently formed. Taken on April 1, 1995, it was named one of the top ten photographs from Hubble by Space.com. The astronomers responsible for the photo were Jeff Hester and Paul Scowen from Arizona State University. The region was rephotographed by ESA's Herschel Space Observatory in 2011, and again by the Hubble in 2014 with a newer camera (see below).

Space Telescope Imaging Spectrograph

The Space Telescope Imaging Spectrograph (STIS) is a spectrograph, also with a camera mode, installed on the Hubble Space Telescope. Aerospace engineer Bruce Woodgate of the Goddard Space Flight Center was the principal investigator and creator of the STIS. It operated continuously from 1997 until a power supply failure in August 2004. After repairs, it began operating again in 2009. The spectrograph has made many important observations, including the first spectrum of the atmosphere of an extrasolar planet, HD 209458b.

The STIS was installed on Hubble in 1997 during its second servicing mission (STS-82) by Mark Lee and Steven Smith, replacing the High Resolution Spectrograph and the Faint Object Spectrograph. It was designed to operate for five years. On August 3, 2004 an electronic failure rendered STIS inoperable, ending its use 2 years beyond its predicted lifespan. In order to bring it back to operational status, the instrument was repaired by space shuttle astronauts during STS-125, Servicing Mission 4, launched on May 11, 2009. The crew did a long (many hour) EVA to repair the instrument.

Congratulations, you brought STIS back to life

Wide Field Camera

Hubble Space Telescope instruments:

Wide Field and Planetary Camera

Wide Field and Planetary Camera 2

Wide Field Camera 3

Wide Field Camera, an instrument at Isaac Newton TelescopeOther Satellite instruments:

Wide Field Camera, an instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)

Wide Field Camera 3

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 (Hubble Space Telescope Servicing Mission 4) on May 14, 2009.

Wide Field and Planetary Camera

The Wide Field/Planetary Camera (WFPC) (pronounced as wiffpick (Operators of the WFPC1 were known as "whiff-pickers")) was a camera installed on the Hubble Space Telescope until December 1993. It was one of the instruments on Hubble at launch, but its functionality was severely impaired by the defects of the main mirror optics which afflicted the telescope. However, it produced uniquely valuable high resolution images of relatively bright astronomical objects, allowing for a number of discoveries to be made by HST even in its aberrated condition.

WFPC was proposed by James A. Westphal, a professor of planetary science at Caltech, and was designed, constructed, and managed by JPL. At the time it was proposed, 1976, CCDs had barely been used for astronomical imaging, though the first KH-11 KENNEN reconnaissance satellite equipped with CCDs for imaging was launched in December 1976. The high sensitivity offered such promise that many astronomers strongly argued that CCDs should be considered for Hubble Space Telescope instrumentation.

This first WFPC consisted of two separate cameras, each comprising 4 800x800 pixel Texas Instruments CCDs arranged to cover a contiguous field of view. The Wide Field camera had a 0.1 arcsecond pixel scale and was intended for the panoramic observations of faint sources at the cost of angular resolution. The Planetary Camera had a 0.043 arcsecond pixel scale and was intended for high-resolution observations. Selection between the two cameras was done with a four-facetted pyramid that rotated by 45 degrees.As part of the corrective service mission (STS-61 in December 1993) the WFPC was swapped out for a replacement version. The Wide Field and Planetary Camera 2 improved on its predecessor and incorporated corrective optics needed to overcome the main mirror defect. To avoid potential confusion, the WFPC is now most commonly referred to as WFPC1.

On its return to Earth, the WFPC was disassembled and parts of it were used in Wide Field Camera 3, which was installed in Hubble on May 14, 2009 as part of Servicing Mission 4, replacing WFPC2.

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