Advanced Camera for Surveys. The ACS contains three cameras; the wide field camera WFC, the high-resolution camera HRC, and the solar blind camera SBC.
ACS grism data are slitless spectra acquired with the Advanced Camera for Surveys grism mode. The
Space Telescope European Coordinating Facility (ST-ECF) has created data products for the HLA by extracting and
calibrating the spectra of individual objects in the ACS grism observations.
Cosmic Origin Spectrograph. Installed in May 2009 during SM4, COS is best at observing points of light, like stars and quasars. COS focuses exclusively on ultraviolet light and has two channels, one to examine far-ultraviolet light, and one to examine near-ultraviolet light.
Energetic particles traveling through space at high velocity. CRs create image artifacts (bright pixels) in exposures and need be removed in the image
processing by combining multiple exposures or by filtering based on the shapes of the artifacts.
Data Archive and Distribution System. This is the "classic" archive retrieval system for Hubble data. Data that are not yet in the HLA
will be usually be available through DADS. Observations taken within the past year are often proprietary, meaning that
special archive account privileges are required for data retrieval.
Digitized Sky Survey. The DSS comprises a set of all-sky photographic
surveys in E, V, J, R, and N bands conducted with the Palomar and
UK Schmidt telescopes. The glass photographic plates were scanned
and digitized by STScI for the Guide Star Catalog projects. The HLA
uses color images created by combining red and blue DSS plates as the
background image in the footprints view.
Faint Images of the Radio Sky at Twenty-cm.
FIRST is a project designed to produce
the radio equivalent of the Palomar Observatory Sky Survey over 9,000
square degrees of the North and South Galactic Caps. Data from the NRAO Very
Large Array (VLA) are reduced using an automated mapping pipeline to produce images
with 1.8" pixels, a typical rms of 0.15 mJy, and a resolution of 5". At
the 1 mJy source detection threshold, there are ~90 sources per square
degree, ~35% of which have resolved structure on scales from 2-30". 30%
of the sources have counterparts in the Sloan Digital Sky Survey.
Flexible Image Transport System.
FITS is the standard astronomical
data format endorsed by both NASA and the IAU. FITS is much more than
an image format (such as JPEG or GIF) and is primarily designed to store
scientific data sets consisting of multi-dimensional arrays (1-D spectra,
2-D images or 3-D data cubes) and 2-dimensional tables containing rows
and columns of data.
Faint Object Spectrograph. The FOS was designed to make spectroscopic
observations of astrophysical sources from the near ultraviolet to the
near infrared (1150 - 8000 Angstroms).
It was used from the Hubble launch in 1990 until its removal in 1997.
The Galaxy Evolution Explorer. GALEX is a NASA mission led
by the California Institute of Technology aimed at investigating how
star formation in galaxies evolved from the early Universe up to the
present. GALEX uses microchannel plate detectors to obtain direct images
in the near-UV (NUV) and far-UV (FUV) and a grism to disperse light for
spectroscopy. The GALEX data archive
is located at MAST; GALEX data products
include a series of all sky surveys and deep sky surveys in the imaging
mode and partial surveys in the near and far UV spectroscopic modes.
Goddard High Resolution Spectrograph. The GHRS was a high-resolution
spectrograph operating in the ultraviolet.
It was used from the Hubble launch in 1990 until its removal in 1997.
Guide Star Catalog 2.
The Guide Star
Catalog 2 is an all-sky optical catalog based on the 1" resolution scans
of the photographic Sky Survey plates (the DSS),
at two epochs and three bandpasses, from the Palomar and UK Schmidt telescopes.
It includes positions, magnitudes and classifications for approximately
1 billion (109) objects.
A combination of a prism and grating arranged to keep light at a chosen central wavelength undeviated as it passes through the grism. The resolution of a grism is proportional to the tangent of the wedge angle of the prism in much the same way as the resolution of gratings are proportional to the angle between the input and the normal to the grating. The grism then creates a dispersed spectrum centered on the location of the object in the camera field of view.
High Resolution Camera.
This is one of the 3 imaging channels on the ACS.
The HRC was a high-resolution CCD camera with 0.025 arcsecond pixels (half the size of the
WFC pixels). With a field of view only 22 arcsec wide, it was used to make
the highest resolution images of small sky areas from the near infrared to the near ultraviolet.
It also included a coronagraphic mode to suppress the light from
bright astronomical sources, allowing for much fainter objects to be detected nearby.
The HRC is inoperable due to the power supply failure in January 2007; it was not able to be
repaired in the servicing mission in May 2009.
Multi-mission Archive at the Space Telescope.
The Multimission Archive at STScI
is a NASA funded project to support and provide to the astronomical
community a variety of astronomical data archives, with the primary
focus on scientifically related data sets in the optical, ultraviolet,
and near-infrared parts of the spectrum. The HLA project is part of
MAST, as are many other archival products and services used by the HLA including
DADS, DSS, GSC2,
GALEX, FIRST,
Kepler, etc.
MultiDrizzle combines dithered observations (different overlapping
pointings that are shifted or rotated) to create combined images. It can
correct for geometrical distortion in the camera, can orient the combined
image to have north up (which is not the case for raw Hubble images),
and automates and simplifies the detection of
cosmic-rays. It is implemented using
the Python scripting language and PyRAF, the Python-based interface
to IRAF.
The Near Infrared Camera and Multi-Object Spectrometer. The NICMOS provides imaging capabilities in broad, medium, and narrow band filters, broad-band imaging polarimetry, coronographic imaging, and slitless grism spectroscopy, in the wavelength range 0.8-2.5 microns. NICMOS has three adjacent but not contiguous cameras, designed to operate independently, each with a dedicated array at a different magnification scale.
NICMOS grism data are slitless spectra acquired with the
NICMOSgrism mode. The Space
Telescope European Coordinating Facility (ST-ECF) has created
data products for the HLA by extracting and calibrating the spectra of
individual objects in the NICMOS grism observations.
Photometry is the term used for the study of light emitted by a star or other astronomical object. This brightness is generally defined in absolute terms.
Right Ascension. The RA is the value of a longitudinal angle as it
occurs in the equitorial coordinate system. It is measured in hours,
minutes, and seconds, or it may also be measured in decimal degrees
(with 360 degrees = 24 hours).
Solar Blind Camera.
This is one of the 3 imaging channels on the ACS.
It uses an ultraviolet-sensitive photon-counting detector to observe small faint regions at
wavelengths inaccessible to CCD detectors. It is deliberately designed not to have
any sensitivity to photons at the longer visible wavelengths of light in order to
allow accurate measurements of the faint ultraviolet brightness of objects that
are very bright at redder wavelengths. The detector is the same model as is used
in the STIS UV detectors.
Sloan Digital Sky Survey. The SDSS used a dedicated 2.5-meter telescope at Apache Point Observatory, New Mexico to obtain deep, multi-color images covering more than a quarter of the sky and acquired spectra to measure redshifts for more than 930,000 galaxies and 120,000 quasars.
Spectroscopy is the use of light, sound or particle emission to study matter. The emissions are, in many cases, able to provide information about the properties of the matter under investigation. The device often used for such analysis is a spectrometer, which records the spectrum of light emitted (or absorbed) by a given material, especially in analytical chemistry and physical chemistry fields, where the light can be used to determine the chemical composition of a substance because of signature spectral lines emitted by known elements.
Space Telescope Imaging Spectrograph. The instrument provides spatially resolved spectroscopy from 1150 to 10,300 Å at low to medium spectral resolution, high spatial resolution echelle spectroscopy in the ultraviolet, solar-blind imaging in the ultraviolet, time tagging of photons in the ultraviolet for high time resolution, and direct and coronagraphic imaging in the optical.
Two Micron All Sky Survey. 2MASS
has uniformly scanned the entire sky in three near-infrared bands to detect and characterize point sources brighter than about 1 mJy in each band, with signal-to-noise ratio (SNR) greater than 10, using a pixel size of 2.0". 2MASS used two highly-automated 1.3-m telescopes, one at Mt. Hopkins, AZ, and one at CTIO, Chile. Each telescope was equipped with a three-channel camera, each channel consisting of a 256×256 array of HgCdTe detectors, capable of observing the sky simultaneously at J (1.25 microns), H (1.65 microns), and Ks (2.17 microns).
World Coordinate System. The WCS convention defines keywords and usage
that provide for the description of astronomical coordinate systems in
a FITS image header.
Wide Field Camera.
This is one of the 3 imaging channels on the ACS.
The WFC is the most utilized channel of ACS that conducts broad surveys of the universe. Its detector consists of two butted 2048x4096, 15 µm/pixel charge-coupled devices (CCDs) for a total of 16 megapixels. The WFC plate scale is 0.05″ per pixel and it has an effective field-of-view of 202″×202″. The spectral range of the WFC detector is 350-1100 nm.
Wide Field Camera 3. Installed in May 2009 during SM4, WFC3 observes near-infrared light, visible light, and near-ultraviolet radiation. WFC3 has two "channels." Each channel detects and processes different wavelengths. The ultraviolet-visible channel can be used to study nearby galaxies and galaxies undergoing bursts of star formation. The near-infrared channel can be used to study the light from distant galaxies.
Wide Field Planetary Camera-2. The WFPC2 was used to obtain high
resolution images of astronomical objects over a relatively wide field
of view and a broad range of wavelengths (1150 to 11,000 Å). WFPC2
includes 4 800x800 CCDs, three with 0.1" pixels (the WF channels) and
one with 0.05" pixels (the PC). Most observations include data from all
4 CCDs. The HLA includes two different data products for most WFPC2
observations. The WFPC2 images have all 4 CCDs combined onto a
0.1" pixel scale that matches the WF CCDs; the WFPC2-PC images
include only the PC chip and have a 0.05" pixel scale. These images
can be selected separately using the WFPC2 and WFPC2-PC instrument choices
in the HLA advanced search options. The WFPC2 operated from 1994 until
its replacement in the May 2009 servicing mission.
