An astronomical survey is a general map or image of a region of the sky which lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of many images or spectra of objects which share a common type or feature. Surveys are often restricted to one band of the electromagnetic spectrum due to instrumental limitations, although multiwavelength surveys can be made by using multiple detectors, each sensitive to a different bandwidth. Surveys have generally been performed as part of the production of an astronomical catalog.
Sky surveys, unlike targeted observation of a specific object, allow astronomers to catalogue celestial objects and perform statistical analyses on them without making prohibitively lengthy observations. In some cases, an astronomer interested in a particular object will find that survey images are sufficient to make telescope time entirely unnecessary.
Surveys also help astronomers obtain observation time on larger, more powerful telescopes. If the astronomer can show a telescope scheduling committee that previous observations support his or her hypothesis, he or she is more likely to be given a chance to make more detailed observations.
The wide scope of surveys makes them ideal for astronomers searching for moving foreground objects such as asteroids and comets. An astronomer can compare existing survey images to current observations to locate targets which are in motion; this task can even be performed automatically using image analysis software. Similarly, images of the same object taken by different surveys can be compared to detect transient events such as variable stars.
Optical
Pan-Andromeda Archaeological Survey
National Geographic Society – Palomar Observatory Sky Survey (NGS–POSS) – survey of the northern sky on photographic plates, 1948–1958
CfA Redshift Survey – A program from Harvard-Smithonian Center for Astrophysics. It began in 1977 to 1982 then from 1985 to 1995.
Digitized Sky Survey – optical all-sky survey created from digitized photographic plates, 1994
2dF Galaxy Redshift Survey (2dfGRS) – redshift survey conducted by the Anglo-Australian Observatory between 1997 and 2002
Sloan Digital Sky Survey (SDSS) – an optical and spectroscopic survey, 2000–2006 (first pass)
Photopic Sky Survey – a survey with 37,440 individual exposures, 2010–2011.
DEEP2 Redshift Survey (DEEP2) – Used Keck Telescopes to measure redshift of 50,000 galaxies
VIMOS-VLT Deep Survey (VVDS) – Franco-Italian study using the Very Large Telescope at Paranal Observatory
Palomar Distant Solar System Survey (PDSSS)
WiggleZ Dark Energy Survey (2006–2011) used the Australian Astronomical Observatory
Dark Energy Survey (DES) is a survey about one-tenth of the sky to find clues to the characteristics of dark energy.-
Calar Alto Legacy Integral Field Area Survey (CALIFA) – a spectroscopic survey of galaxies
SAGES Legacy Unifying Globulars and GalaxieS (SAGES Legacy Unifying Globulars and GalaxieS Survey (SLUGGS) survey – a near-infrared spectro-photometric survey of 25 nearby early-type galaxies (2014)
Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) – an extra-galactic and stellar spectroscopic survey
IPHAS and VPHAS+ – surveys of the Galactic bulge and inner disk using the Isaac Newton Telescope (north) and VLT Survey Telescope (south) in u, g, r, Hα, and i bands, 2003–present
Infrared
Infrared Astronomical Satellite did an all sky survey at 12, 25, 60, and 100 μm, 1983
The 2-micron All-Sky Survey (2MASS), a ground based all sky survey at J, H, and Ks bands (1.25, 1.65, and 2.17 μm) 1997–2001
Akari (Astro-F) a Japanese mid and far infrared all-sky survey satellite, 2006–2008
Wide-field Infrared Survey Explorer (WISE) was launched in December 2009 to begin a survey of 99% of the sky at wavelengths of 3.3, 4.7, 12, and 23 μm. The telescope is over a thousand times as sensitive as previous infrared surveys. The initial survey, consisting of each sky position imaged at least eight times, was completed by July 2010.
UKIRT Infrared Deep Sky Survey (UKIDSS) – a collection of ground based northern hemisphere surveys (GPS, GCS, LAS, DXS, UDS) using the WFCAM camera on UKIRT, some wide and some very deep, in Z, Y, J, H, & K bands 2005–
VISTA public surveys – a collection of ground based southern hemisphere surveys (VVV, VMC, VHS, VIKING, VIDEO, UltraVISTA), of various areas and depths, in Z, Y, J, H, & Ks bands, 2009–present
SCUBA-2 All Sky Survey
Radio
HIPASS – Radio survey, the first blind HI survey to cover the entire southern sky. 1997–2002
Ohio Sky Survey – Over 19,000 radio sources at 1415 MHz. 1965–1973.
NVSS – Survey at 1.4 GHz mapping the sky north of −40 deg
FIRST – Survey to look for faint radio sources at twenty cms.
PALFA Survey – On-going 1.4 GHz survey for radio pulsars using the Arecibo Observatory.
GALEX Arecibo SDSS Survey GASS designed to measure the neutral hydrogen content of a representative sample of ~1000 massive, galaxies
C-BASS – On-going 5 GHz all sky survey to aid in the subtraction of galactic foregrounds from maps of the Cosmic Microwave Background
Gamma-ray
Fermi Gamma-ray Space Telescope, formerly referred to as the "Gamma-ray Large Area Space Telescope (GLAST)." 2008–present; the goal for the telescope's lifetime is 10 years.
Multi-wavelength surveys
GAMA – the Galaxy And Mass Assembly survey combines data from a number of ground- and space-based observatories together with a large redshift survey, performed at the Anglo-Australian Telescope. The resulting dataset aims to be a comprehensive resource for studying the physics of the galaxy population and underlying mass structures in the recent universe.
GOODS – The Great Observatories Origins Deep Survey.
COSMOS – The Cosmic Evolution Survey
(The latter two surveys are joining together observations obtained from space with the Hubble Space Telescope, the Spitzer Space Telescope, the Chandra X-ray Observatory and the XMM-Newton satellite, with a large set of observations obtained with ground-based telescopes).
Atlas 3d Survey – sample of 260 galaxies for the Astrophysics project.
Planned
Pan-STARRS – a proposed 4-telescope large-field survey system to look for transient and variable sources
Large Synoptic Survey Telescope – a proposed very large telescope designed to repeatedly survey the whole sky that is visible from its location
ASKAP HI All Sky Survey (WALLABY) – PI Bärbel Koribalski
The Magellanic Clouds Photometric Survey – UBVI (optical)
Deep Near Infrared Survey (DENIS) – near-IR
