BOX 1-2

Digital Data in Astronomy

As astronomical observatories have become more powerful, they also have become more data-intensive.a Table 1-1 shows the trend in recent decades. The Sloan Digital Sky Survey (SDSS), for example, has delivered an unprecedented flood of data since it began operation in 2000. The SDSS uses a dedicated 2.5-meter telescope on Apache Point, New Mexico, equipped with two special-purpose instruments. The telescope’s camera can image 1.5 square degrees of sky at a time—about eight times the area of the full moon. A pair of spectrographs can measure spectra of—and hence

TABLE 1-1 Data Trends in Astronomy Research

Cosmic Microwave Background (CMB) Surveys: Collect information used to understand the origin and evolution of the universe

Year

Survey

Data items (pixels)

1990

Cosmic Background Explorer (COBE)

1,000

2000

Boomerang (balloon-borne millimeter-wave telescope)

10,000

2002

Cosmic Background Imager (CBI)

50,000

2003

Wilkinson Microwave Anisotropy Probe (WMAP)

1,000,000

2009

Planck

10,000,000

Galaxy Surveys: Collect two dimensional optical images of galaxies and quasars

Year

Survey

Objects

1970

Lick Observatory

1,000,000

1990

Automatic Plate Measuring Facility (APM)

2,000,000

2005

Sloan Digital Sky Survey (SDSS)

200,000,000

2009

Visible and Infrared Telescope for Astronomy (VISTA)

1,000,000,000

2015

Large Synoptic Survey Telescope (LSST)1

20,000,000,000

Galaxy Redshift Surveys: Collect three dimensional optical catalogs of galaxies and quasars

Year

Survey

Objects

1986

Center for Astrophysics (CfA)

3,500

1996

Las Campanas Redshift Survey (LCRS)

23,000

2003

2dF Galaxy Redshift Survey

250,000

2005

Sloan Digital Sky Survey (SDSS)

750,000

2007

SDSS color-redshift survey

20,000,000

2015

LSST color-redshift survey

4,000,000,000

NOTE: There are 100 billion galaxies in the observable universe, meaning that LSST will record about 20 percent.

Source: Presentation to the committee by Alex Szalay, Johns Hopkins University, December 2007, updated in 2008 with comments by Tony Tyson and Michael Turner.



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