7.3 Hubble Legacy Archive (HLA)

The Hubble Legacy Archive (HLA) is a project designed to enhance science from the Hubble Space Telescope by augmenting the HST Data Archive and by providing advanced browsing capabilities. It is a joint project of the Space Telescope Science Institute, the Canadian Astronomy Data Centre (CADC), and the European Space Astronomy Centre (ESAC). The primary enhancements are:

•	Advanced data products with several HST instruments, produced for public data.

•	Data products that are immediately available online for viewing, searching and downloading.

•	A footprint service that makes it easier to browse and download images.

•	Availability of combined images, prototype mosaics, and spectral data.

•	For many images, the absolute astrometry has been improved from one to two arcsec to ~0.3 arcsec.

•	Source lists are available for ACS, WFPC2, and WFC3 observations.

•	NICMOS and ACS grism extractions have been produced by European Coordinating Facility (ST-ECF).

•	An interface is provided for many user-provided High Level Science Products.

At this writing (December 2012), the HLA has completed its seventh major Data Release, including enhanced data products for almost all public science data for ACS, WFPC2 (produced by CADC), and NICMOS, as well as WFC3 data through the end of 2011. Also available are source lists for ACS, WFPC2, and WFC3. Some STIS spectra are also available as high level science products, and can be searched, viewed, and retrieved through the same interface as enhanced image data. Multi-visit ACS mosaics have been produced for 67 pointings. The footprint service shows the outline of data from all instruments, including data that are still proprietary, and an interface to the main HST Archive is provided to access proprietary data (for PIs and their designated collaborators) and recent data for which enhanced HLA products are not yet available.

Some of the more general goals of the HLA are to make HST data VO-compatible (Virtual Observatory), to move toward a sky atlas user view rather than a collection of datasets, and to develop an “all-HST-sky” source list. The HLA can be accessed at:

http://hla.stsci.edu.