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, until December 2010, the European Coordinating Facility (ST-ECF). The primary enhancements are:

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

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

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

•	Combined images and prototype mosaics are available.

•	For many images, the absolute astrometry has been improved from 1 - 2 arcsec to ~0.3 arcsec.

•	Source lists are available for ACS and WFPC2 observations.

•	NICMOS and ACS grism extractions have been produced by ST-ECF.

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

At this writing, the HLA has completed its fifth major Data Release, including enhanced data products for almost all public science data for ACS, WFPC2 (produced by CADC), and NICMOS through mid-2011, as well as source lists for ACS and WFPC2. Similar products will be available for WFC3 starting in early 2012. Some COS data are available as high-level science products, and 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 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 (Virtual Observatory) compatible, 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.