Up to 10% of the available JWST observing time may be reserved for Director’s Discretionary (DD) allocation. Scientists wishing to request DD time can do so at any time during the year, by using APT. A Director's Discretionary (DD) time proposal is appropriate when a truly unexpected transient phenomenon occurs or when developments since the last proposal cycle present a scientifically urgent case for new observations. The pool of JWST time for in-cycle DD proposals is limited. DD proposals are typically small,  <15 hours. Larger requests can be considered under exceptional circumstances but are generally better suited to the standard observing cycle and the TAC review process.

Starting in Cycle 2, joint JWST-HST DD proposals are permitted.  All joint JWST-HST proposals should be submitted using the JWST APT. Joint DD proposals with other facilities are not permitted.

Observations obtained as part of a DD program generally do not have an exclusive access period, and are made available immediately to the astronomical community. However, DD proposers may request and justify such periods in their proposals. Such requests will only be granted under exceptional circumstances. Upon receipt of a DD Proposal, the STScI Director will usually seek advice on the scientific merit and technical feasibility of the proposal from STScI staff and external specialists.

Proposers may apply for time-critical DD observations for transient phenomena. They may also submit Discovery DD proposals to address topics of compelling urgency that will significantly accelerate scientific discovery.  Additional information is available at Cycle 3 Director's Discretionary (DD) Time Proposals.

Large-scale DD initiatives

STScI Directors have used substantial portions of DD time, on occasion, for major scientific initiatives. The prototype for this use of DD time was the Hubble Deep Field observations in 1994, a revolutionary set of observations that had enormous impact on the course of astronomy, and on the public imagination. These observations were followed up on Hubble with similar campaigns for the Hubble Deep Field South, the Ultra Deep Field, the WFC3 Early Release Science programs, the Frontier Fields, and ULLYSES. 

Early Release Science Program

On JWST, the Director's Discretionary (DD) Early Release Science (ERS) Program was established to help maximize the science return. To increase the number and breadth of JWST observations that were public in time for GO Cycle 2 proposal preparation, the Director allocated 530 hours of Cycle 1 DD time to 13 community-led ERS programs. The majority of these observations, encompassing a wide range of science cases, instruments and observing modes, were acquired in the first 5 months of science operations and become public immediately. The ERS teams produced data deliveries shortly, including high-level data products, software tools, Jupyter notebooks, documentation, instrument performance, simulations, ancillary data, and community engagement events.

Rocky Worlds Director’s Discretionary Time program

The STScI Director, Dr. Jennifer Lotz, has accepted the primary recommendation of the Working Group on Strategic Exoplanet Initiatives, and has decided to proceed with a large-scale survey of rocky M-dwarf exoplanets. The program will use around 500 hours of Director’s Discretionary Time on the James Webb Space Telescope to search for atmospheres in more than a dozen nearby systems. Approximately 250 orbits of ultraviolet observations with the Hubble Space Telescope will be used to characterize the activity of the host stars. The observations will be executed by an STScI Core Implementation Team led by Dr. Nestor Espinoza, supported by Dr. Hannah Diamond-Lowe as the team Deputy. Community input will be sought on the target list and an initial set of high priority targets and observing plans will be announced by mid-September, well in advance of the Cycle 4 deadline. The community is encouraged to consider complementary and supplementary programs for those targets.