sci25010 — Announcement

Hubble Spectroscopic Legacy Archive products now available in the eHST Science Archive

17 December 2025

- By Chris Evans, Javier Espinosa Aranda, Victor Fernández Rubio, María Arévalo Sánchez, Deborah Baines, Monica Fernández Barreiro, Marcos López-Caniego Alcarria, Bruno Merín Martin, Laura Masselos, Paule Sonnentrucker -

The European Hubble Space Telescope (eHST) Science Archive is hosted at ESA’s European Space Astronomy Centre (ESAC). As part of ESA’s multi-decade partnership with NASA on the mission, the eHST archive provides a European mirror of all public Hubble data in the Mikulski Archive for Space Telescopes (MAST) archive at the Space Telescope Science Institute (STScI).

We are pleased to announce the release of a new version of eHST, which now includes science products from the Hubble Spectroscopic Legacy Archive (HSLA), that were released by STScI in November 2025. In brief, the HSLA provides co-added spectra of each individual target observed by Hubble’s Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS). To maximise the signal-to-noise and wavelength coverage for each target, the HSLA automatically combines data from multiple observing programmes, instruments and gratings, as well as classifying targets to enable searches on the basis of object classification.

The HSLA currently has combined spectra for over 3000 individual stars and more than 2000 individual galaxies. Moreover, the HSLA automatically updates the products for each target as new data become publicly available, or if there are updates to the data calibration. An example co-added HLSA spectrum is shown in Image B from three separate COS and STIS gratings of β Pictoris. Further details of the HSLA, including links to notebooks to create custom products, are available here.

The HSLA products are included seamlessly in eHST, with them displayed in the results table for a given target (see Image C). ESASky is also fully integrated in the results table to enable effective cross-matching with data and catalogues from ESA’s missions and data products from other astronomical facilities. Quick previews are available for each HSLA spectrum in the results table, as well as an interactive spectral viewer for more detailed inspection.

Other new features in the latest version of eHST include an updated image viewer for quick-look visualization and a new data download panel, allowing you to filter and retrieve exactly the individual files required for your research. We encourage you to explore the HSLA and these latest features, and to provide us with your feedback via the ESDC Helpdesk.