To appear in Astronomical Techniques, Software, and Data (ed. H. Bond), Vol.2 of Planets, Stars, and Stellar Systems (ser. ed. T. Oswalt), Springer Verlag, in press (2012)
astro-ph/1203.5111

For a PDF version of the article, click here.

SKY SURVEYS

S. G. Djorgovski, A.A. Mahabal, A.J. Drake, M.J. Graham, and C. Donalek


California Institute of Technology Pasadena, CA 91125, USA


Abstract: Sky surveys represent a fundamental data basis for astronomy. We use them to map in a systematic way the universe and its constituents, and to discover new types of objects or phenomena. We review the subject, with an emphasis on the wide-field, imaging surveys, placing them in a broader scientific and historical context. Surveys are now the largest data generators in astronomy, propelled by the advances in information and computation technology, and have transformed the ways in which astronomy is done. This trend is bound to continue, especially with the new generation of synoptic sky surveys that cover wide areas of the sky repeatedly, and open a new time domain of discovery. We describe the variety and the general properties of surveys, illustrated by a number of examples, the ways in which they may be quantified and compared, and offer some figures of merit that can be used to compare their scientific discovery potential. Surveys enable a very wide range of science, and that is perhaps their key unifying characteristic. As new domains of the observable parameter space open up thanks to the advances in technology, surveys are often the initial step in their exploration. Some science can be done with the survey data alone (or a combination of data from different surveys), and some requires a targeted follow-up of potentially interesting sources selected from surveys. Surveys can be used to generate large, statistical samples of objects that can be studied as populations, or as tracers of larger structures to which they belong. They can be also used to discover or generate samples of rare or unusual objects, and may lead to discoveries of some previously unknown types. We discuss a general framework of parameter spaces that can be used for an assessment and comparison of different surveys, and the strategies for their scientific exploration. As we are moving into the Petascale regime and beyond, an effective processing and scientific exploitation of such large data sets and data streams poses many challenges, some of which are specific to any given survey, and some of which may be addressed in the framework of Virtual Observatory and Astroinformatics. The exponential growth of data volumes and complexity makes a broader application of data mining and knowledge discovery technologies critical in order to take a full advantage of this wealth of information. Finally, we discuss some outstanding challenges and prospects for the future.


Table of Contents

INTRODUCTION
Definitions and Caveats
The Types and Goals of Sky Surveys
The Data Explosion

A (VERY) BRIEF HISTORY OF SKY SURVEYS

A SYSTEMATIC EXPLORATION OF THE SKY
The Role of Technology
Data Parameter Spaces
Exploring the Parameter Spaces

CHARACTERISTICS AND EXAMPLES OF SKY SURVEYS
A Sampler of Panoramic Sky Surveys and Catalogs
Synoptic Sky Surveys and Exploration of the Time Domain
Towards the Petascale Data Streams and Beyond
Deep Field Surveys
Spectroscopic Surveys
Figures of Merit

FROM THE RAW DATA TO SCIENCE-READY ARCHIVES
Data Processing Pipelines
Source and Event Classification
Data Archives, Analysis and Exploration

CONCLUDING COMMENTS

APPENDIX: A PARTIAL LIST OF SKY SURVEYS, FACILITIES, AND ARCHIVES AS OF 2011

REFERENCES



We dedicate this Chapter to the memory of three pioneers of sky surveys, Fritz Zwicky (1898-1974), Bogdan Paczynski (1940-2007), and John Huchra (1948-2010).


Index Terms: Sky surveys; synoptic surveys; wide-field surveys; deep surveys; catalogs; archives; technology; virtual observatory (VO); astroinformatics; data processing pipelines; digital imaging; astronomical photography; observable parameter space (OPS); measurement parameter space (MPS); physical parameter space (PPS); time domain; multi-wavelength astronomy; data mining; classification; systematic exploration; figures of merit for sky surveys; statistical studies; software; pipelines; history of astronomy.


Keywords:

Sec. 1: Sky surveys; synoptic surveys; wide-field surveys; deep surveys; catalogs; archives; virtual observatory (VO); digital imaging; astronomical photography; multi-wavelength astronomy.

Sec. 2: Sky surveys; history of astronomy; astronomical photography; space-based astronomy.

Sec. 3: Technology; observable parameter space (OPS); measurement parameter space (MPS); physical parameter space (PPS); time domain; multi-wavelength astronomy; data mining; classification; systematic exploration; statistical studies.

Sec. 4: Sky surveys; synoptic surveys; wide-field surveys; deep surveys; catalogs; archives; multi-wavelength astronomy; supernova surveys; asteroid surveys; microlensing surveys; time domain; figures of merit for sky surveys.

Sec. 5: Software; technology; data processing pipelines; archives; virtual observatory (VO); astroinformatics; data mining; classification; time domain.

Sec. 6:

Entire Chapter: Same as the Index Terms.

Cross-References:

TBD

List of Selected Abbreviations:

AAVSO = American Association of Variable Star Observers, http://www.aavso.org/
CCD = Charge Coupled Device
CfA = Harvard-Smithsonian Center for Astrophysics, http://cfa.harvard.edu
CFHT = Canada-France-Hawaii Telescope, http://www.cfht.hawaii.edu
CMBR = Cosmic Microwave Background Radiation
EB = Exabyte (1018 bytes)
ESO = European Southern Observatory, http://eso.org
FITS = Flexible Image Transport System, http://heasarc.nasa.gov/docs/heasarc/fits.html
FoM = Figure of Merit
FOV = Field of view
FWHM = Full Width at Half Maximum
GB = Gigabyte (109 bytes)
HST = Hubble Space Telescope, http://www.stsci.edu/hst
ICT = Information and Computing Technology
LSS = Large-Scale Structure
MB = Megabyte (106 bytes)
NOAO = National Optical Astronomy Observatory, http://noao.edu
NRAO = National Radio Astronomy Observatory, http://nrao.edu
MJD = Modified Julian Date
MPS = Measurement Parameter Space
OPS = Observable Parameter Space
PB = Petabyte (1015 bytes)
PPS = Physical Parameter Space
SETI = Search for Extraterrestrial Intelligence, http://www.seti.org
SN = Supernova
TB = Terabyte (1012 bytes)
USNO = United States Naval Observatory, http://www.usno.navy.mil/
VLA = NRAO Very Large Array, http://www.vla.nrao.edu
VO = Virtual Observatory, http://www.ivoa.net
WWT = WorldWide Telescope, http://www.worldwidetelescope.org

Additional abbreviations for the various sky surveys and catalogs are listed in the Appendix.

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