The Hubble Legacy Archive (HLA) is designed to optimize science from the Hubble Space Telescope by providing online, enhanced Hubble products and advanced browsing capabilities. The HLA is a joint project of the Space Telescope Science Institute (STScI), the Space Telescope European Coordinating Facility (ST-ECF), and the Canadian Astronomy Data Centre (CADC).

Hubble Catalog of Variables (2019 September 24)

• The Hubble Catalog of Variables (HCV), a major new High-Level Science Product derived from the Hubble Source Catalog, was released. The HCV is the first homogeneous catalog of variable sources found in the HSC. It includes variable stars in our Galaxy and nearby galaxies, as well as transients and variable active galactic nuclei.
• The HCV is fully integrated with the MAST user interfaces for the HSC, including the HSC CasJobs and VO TAP database query interfaces and the MAST catalogs simple form interface and query API. There are Python Jupyter notebooks available that show how to access the data in scripts. The ESAC Science Data Centre has created the HCV Explorer, a new online web tool to access, visualize, and interactively explore the HCV.

Hubble Source Catalog Version 3.1 (2019 June 27)

• HSC version 3.1 was released on 2019 June 26. It adds proper motions of over 400,000 objects in the SWEEPS field. The proper motion information is available in database tables within the HSCv3 context of the STScI CasJobs interface.
• We also provide a Python Jupyter notebook that queries the HSCv3 database through a Python interface to CasJobs. More details about HSC v3.1 are found here.

HLA DR10.1 and Hubble Source Catalog Version 3 (2018 July 5)

NEW DATA PRODUCTS

• Source lists from HLA DR10 have been combined to create version 3 of the Hubble Source Catalog. See the HSC Home Page for details and data access links.
• There are approximately 25% more ACS source lists and almost twice as many WFC3 source lists compared with HSC v2.
• The source list photometric quality is significantly improved.
• Improved astrometric calibration is based on the Gaia DR1 catalog. Shifts up to 100 arcsec have been correctly identified. 94% of the fields have matches to an external astrometric reference catalog.
• The scatter in magnitudes is measured using the median absolute deviation (MAD) of the differences from the median magnitude for more robust estimates.

USER INTERFACE ENHANCEMENTS

• HSCv3 astrometric corrections are used for image cutouts and in the interactive display.
• The HSCv3 catalog is available for overlay in the interactive display. The older HSCv2 and HSCv1 catalogs are also accessible using the HSC Controls in the interactive display.

HLA DR10 Release (2018 January 8)

NEW DATA PRODUCTS

• All ACS and WFC3 data that were public as of 2017 October 1 have been processed. The new image processing pipeline fixes numerous data problems, including corrections for alignment shifts between exposures and a better algorithm for combining short and long exposures. The new source lists have more reliable photometry due both to the image improvements and to better tuning of parameters for the catalog software. All old ACS and WFC3 images have been replaced in this release. These new source lists were used for version 3 of the Hubble Source Catalog, which was released in July 2018.
• New deep, wide-field ACS and WFC3 multi-visit mosaic data products have been generated for 1348 fields. The new mosaic pipeline is based on the processing used for the Hubble Frontier Fields images. These images are astrometrically corrected and aligned using HSC version 2. ACS and WFC3 products are drizzled onto a common pixel grid, which makes them easy to use.

USER INTERFACE ENHANCEMENTS

• Previews and the interactive display handle photon-counting detectors such as the ACS/SBC better.
• Color images for mosaic data products can combine ACS/WFC, WFC3/UVIS and WFC3/IR images.
• The PanSTARRS DR1 catalog is included for overlay in the interactive display.

See the release notes for more details on these and past releases.

HLA ESSENTIALS

• The HLA interface runs in Firefox, Safari, Chrome, Internet Explorer (versions 8* and 9), and similar compatible browsers.
  *IE8 limitations - the scatterplot and plotting tools do not work on IE8 as it does not support HTML5.
• To fully realize all of the HLA's functionality, one must have cookies and popups enabled.
• The HLA includes enhanced data products (ACS, WFC3, WFPC2 & NICMOS images; ACS, WFC3 & WFPC2 source lists; ACS & NICMOS extracted grism spectra; ACS & WFC3 deep/wide mosaic images) and also provides access to the standard HST data products when HLA enhanced products have not yet been created.
• Footprints, which graphically display the sky coverage on a background image from the Digitized Sky Survey, are available for both standard and enhanced HST data products, including extracted grism spectra and community-contributed high-level science products.
• Here is a matrix describing what is and is not in the HLA:

--- The HLA Team
October 2019