Legacy Survey - Data Access

The Legacy Survey data and database are accessible from the NOAO Data Lab, and from the Legacy Survey team website. Explore the dataset interactively using the Sky Viewer.

Data Lab Table Access Protocol (TAP) service

TAP provides a convenient access layer to the Legacy Survey catalog database. TAP-aware clients (such as TOPCAT) can point to http://datalab.noao.edu/tap. For DR3, select the ls_dr3 database, and see the database tables and descriptions. When ready, DR4 will be incorporated in the ls_dr4 database.

Data Lab Query Manager

The Query Manager is available as part of the prototype Data Lab software distribution. The Query Manager client provides a Python API to Data Lab database services. For the Legacy Survey DR3 release, these services include only anonymous access through synchronous queries of the catalog made directly to the database. The full public release of the Data Lab Query Manager in the summer of 2017 will include authenticated access, synchronous and asynchronous queries, TAP queries, personal database storage, and storage through the Data Lab VOSpace.

Image cutouts

The Data Lab Simple Image Access (SIA) service provides a fast way to retrieve cutouts from Legacy Survey images.

Alternatively, sections of the Legacy Survey can be obtained as JPEGs or FITS files using the Legacy Survey team cutout service, as follows:

JPEG: http://legacysurvey.org/viewer/jpeg-cutout/?ra=190.1086&dec=1.2005&layer=decals-dr3&pixscale=0.27&bands=grz

FITS: http://legacysurvey.org/viewer/fits-cutout/?ra=190.1086&dec=1.2005&layer=decals-dr3&pixscale=0.27&bands=grz

where "bands" is a string like "grz","gz","g", etc. Currently, the maximum size for cutouts (in number of pixels) is 512. Pixscale=0.262 will return (approximately) the native DECam pixels.

FTP access

The Legacy Survey DR3 catalog files, images, and products of the photometric pipeline are available by FTP at the NOAO High Level Data Products site (guest connection).

NOAO Science Archive access

The NOAO Science Archive portal can be used to retrieve raw, and calibrated Legacy Survey images, as well as the Tractor catalogs.

  • Query the NOAO Science Archive.
  • From the menu of "Available Collections" on the left, select the desired data release (e.g. DECaLS-DR3).
  • Under "Data products - Raw data" check "Object".
  • Optionally, you may select data from specific DECam filters, or restrict the search by other parameters such as sky coordinates, observing date, or exposure time.
  • Click "Search".
  • For DECaLS only images, refine the search by Proposal ID (2014B-0404) in the "Refine" tab.
The Results page offers several different ways to download the data. See the Tutorials page for details.