Large digital sky surveys, over a broad range of wavelengths, both from the ground and from space observatories, are becoming a major source of astronomical data. Some examples include the Sloan Digital Sky Survey (SDSS) and the Digital Palomar Observatory Sky Survey (DPOSS) in the visible, the Two-Micron All-Sky Survey (2MASS) in the near-infrared, the NRAO VLA Sky Survey (NVSS) and the Faint Images of the Radio Sky at Twenty centimeters (FIRST) in the radio. Many others surveys are planned or expected, in addition to the previously named surveys. While most surveys are exclusively imaging, large-scale spectroscopic surveys also exist. In addition, a number of experiments with specific scientific goals, e.g., microlensing surveys for MACHOs, searches for near-Earth asteroids, are generating comparable data volumes. Typical sizes of resulting data sets (as of the late 1990's) are in the range of tens of Terabytes of digital information, with detections of many millions or even billions of sources, and several tens of parameters measured for each detected source.
This vast amount of new information presents both a great scientific opportunity and a great technological challenge: how to process, and calibrate the raw data; how to store, combine, and access them using modern computing hardware and networks; and how to visualize, explore and analyses these great data sets quickly and efficiently. This is a rapidly developing field, which often entails collaborative efforts between astronomers and computer scientists.
Broadly speaking, the steps along the way include: obtaining the data (telescope/observatory and instrument control software), processing the data into catalogs of detected sources and their observed properties, calibrating the data, archiving the results, and providing the tools for their scientific analysis and exploration.