HST Cycle 27 Special Initiatives

This page describes all proposal types in detail. Proposals can be general observer (GO) or archival (AR) in nature, and can be joint projects with other observatories. STScI also accepts mid-cycle and director's discretionary time proposals.

STScI especially seeks proposals that fall into one of several "Special Initiatives," described below. These initiatives highlight the unique science capabilities possessed by HST.

Ultraviolet Initiative

Ultraviolet GO Proposals

In recognition of the unique UV capabilities of Hubble and the finite lifetime of the mission, the UV Initiative will continue in Cycle 27. The initiative uses orbit allocations to increase the share of primary GO observing time dedicated to UV observations. A description of past HST joint programs is available on the HST UV Initiative Programs webpage.

Both the review panels and the TAC will have UV orbit allocations, which are advisory, not quotas, and UV proposals recommended for acceptance must meet the usual requirement of high scientific quality set for all successful Hubble proposals. Small, Medium, Large, and Treasury GO Proposals can benefit from the UV Initiative, in Cycle 27, as can Archival Proposals. Two conditions must be met for a GO Proposal to be eligible.

• The proposal must use the UV capabilities of Hubble. The eligible instrument modes (with central wavelength <3200 Angstroms) are ACS/SBC imaging (all filters), COS spectroscopy (all modes), STIS/MAMA spectroscopy and imaging (all gratings and filters), STIS/CCD spectroscopy (UV gratings only), and WFC3/UVIS imaging (UV filters F200LP, F300X, F218W, F225W, F275W, FQ232N, FQ243N, and F280N), and WFC3/UVIS G280 grism spectroscopy.

• The UV observations must be essential to the proposed science investigation. This condition will automatically be met for proposals requesting UV observations only. For proposals requesting both UV and optical/IR observations, the scientific necessity for the UV observations must be carefully justified in the Scientific Justification of the proposal.

Proposers must check the UV Initiative box in APT to identify whether their proposal qualifies for the benefit based on the above criteria.

Ultraviolet Archival Proposals

The UV Initiative also extends to Archival Proposals in the Legacy AR category. STScI will ask the review panels and the TAC to give particular consideration to UV-specific archival proposals in the review process, provided they lead to UV high level data products and tools for the Hubble archive, and enable broader use of those datasets by the community, or (in the case of Theory Proposals) provide new models or theories to aid in the interpretation of UV HST data.

For Archival Programs that propose the joint analysis of UV and optical/IR datasets, the UV datasets must be essential to the scientific investigation for the UV Initiative benefit to apply. In this case, the proposers should carefully justify the importance of the UV component of their program in the Special Requirements section of the proposal.

AR proposers should check the "UV Initiative" box in APT to identify their proposal as eligible for the benefit.

JWST Preparatory Observations

The James Webb Space Telescope (JWST) is scheduled to be launched in the spring of 2021. JWST will offer extensive photometric and spectroscopic capabilities spanning the wavelength range 0.7 to 28 microns. Some science programs undertaken with JWST can be enhanced by, and may even require, additional observations. The JWST Initiative is designed to provide an opportunity to obtain observations with Hubble that complement and enhance the scientific impact of JWST observations. In some cases, Hubble observations are essential to achieving critical science goals for future JWST programs. A description of past HST joint programs is available on the JWST Preparatory Programs webpage.

All GO Proposal categories can also be identified as supporting the JWST Initiative. 

Proposers should use the Special Requirements section to describe the connection with specific JWST observations. If the Hubble observations are critical to the success of the future JWST program, the science goals of the full program should be described in the Scientific Justification, including an explanation as to why Hubble observations are deemed essential to achieve those goals. The panels and the TAC will consider the connection between the proposed Hubble and JWST observations as part of the review process. The proposal will be assessed based on the science expectations for the full program, including both the HST and JWST observations. Following the recommendations of the Space Telescope Users Committee, JWST Preparatory proposal data will, by default, not have an exclusive access period (a default of zero months). An exclusive access period may be requested, which will be additionally reviewed by the TAC.

If the Hubble observations are deemed essential to achieving the overall science goals, the proposal will be assessed based on the science expectations for the full program including both Hubble and JWST observations.

Proposers must check the 'JWST Preparatory Science' box in APT to identify whether their proposal qualifies for this initiative.

Fundamental Physics with HST

Over the past quarter century Hubble has played a crucial role in probing parameters relevant to fundamental physics and cosmology. Given that heritage, the STScI Director constituted a working group to explore the intersection between Hubble’s capabilities and the scientific priorities in fundamental physics research and to provide advice on future strategies for implementing appropriate observing programs with HST. The working group’s report highlights a number of areas where they believe HST can make significant contributions in the near future.

STScI encourages the community to submit proposals that address questions in fundamental physics, particularly with regard to the science areas highlighted by the Fundamental Physics Working Group. Those proposals can be for observations (GO), archival research (AR) or theoretical investigations related to HST observations (AR Theory). Given the limited resources available in Cycle 27, proposers may consider pilot investigations that could be expanded in future cycles. The proposals will be reviewed by experts in the appropriate field.

Proposers must check the "Fundamental Physics" box in APT to identify whether their proposal qualifies for this initiative.

Related Links

Report of the Working Group on Fundamental Physics with HST [PDF]

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