Sky Surveys

TL;DR

Sky surveys are essential for mapping the universe, enabling discoveries, statistical studies, and technological advancements in astronomy, driven by large data sets and computational progress.

Contribution

This paper reviews the role, properties, and scientific potential of sky surveys, emphasizing their transformative impact and discussing frameworks for their assessment and exploitation.

Findings

Surveys enable diverse scientific investigations and discoveries.

Advances in technology have significantly increased survey data volumes.

Challenges in data processing are addressed by Virtual Observatory and Astroinformatics.

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 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. We describe the variety and the general properties of surveys, 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; 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. Science can be done with the survey data alone or a combination of different surveys, or with a targeted follow-up of potentially interesting selected sources. Surveys can be used to generate large, statistical samples of objects that can be studied as populations, or as tracers of larger structures. 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 move into the Petascale regime, an effective processing and scientific exploitation of such large data sets and data streams poses many challenges, some of which may be addressed in the framework of Virtual Observatory and Astroinformatics, with a broader application of data mining and knowledge discovery technologies.