Following discussions with the Space Telescope Users Committee, the STScI Director, Ken Sembach, constituted a Working Group to explore the potential for a large-scale program (600-1000 orbits) that takes advantage of Hubble’s unique UV capabilities to probe star formation processes and related stellar astrophysics. The Working Group has submitted its report, recommending that,

 The HST UV Initiative be devoted to obtaining a Hubble UV Legacy Library of Young Stars as Essential Standards (ULLYSES) to serve as a UV spectroscopic reference sample of young high- and low-mass stars. The recommended library will provide observations that uniformly sample the fundamental astrophysical parameter space for each class of stars.

Following external assessment and consultation with the STUC, the Director has decided to implement the program, with observations to be obtained in Cycles 27-29.  Neither the target list nor the detailed observing modes have been defined fully as yet. STScI will constitute an implementation team to work with the community to refine those parameters. All observations will be non-proprietary and available immediately to the community.

The Executive Summary of the Working Group Report is linked here. The full report, which includes some worked examples of potential programs, will be released after the Cycle 27 deadline to avoid potentially misleading the community.

We encourage the community to consider submitting Cycle 27 proposals to supplement and complement the conceptual program. Those proposals might include

    Pure parallel programs that take advantage of spectroscopic observations of OB stars in the Magellanic Clouds and/or low-mass T Tauri stars or brown dwarfs in young Galactic star-forming regions;
    Archival or Theory programs that can utilize or supplement the UV Legacy DD observations. We particularly encourage large-scale programs;
    GO/SNAP programs that can complement UV spectroscopic observations of young stars.

GO programs that are recommended for acceptance by the Cycle 27 TAC have priority over the UV Legacy DD program; TAC-approved observations will not be pre-empted.

For further information on the UV Legacy DD Program, see https://outerspace.stsci.edu/display/HPR/HST+UltraViolet+Legacy+DD+Program+for+Star+Formation+and+related+Stellar+Astrophysics