HST Programs are selected through competitive peer review. A broad range of scientists from the international astronomical community evaluates all submitted proposals, using a well-defined set of criteria (see
Section 6.2) and paying special attention to any potential conflicts of interest. They rank the proposals and offer their recommendations to the STScI Director. Based on these recommendations, the STScI Director makes the final allocation of observing time.
The Review Panels will consider Regular GO (fewer than 100 orbits; see Section 3.2.1), Calibration (
Section 3.2.3), SNAP (
Section 3.3), Regular AR (
Section 3.4.1), Calibration AR (
Section 3.4.3) and Theory (
Section 3.4.4) Proposals. Each Review Panel has an allocation of a specific number of orbits; the Panel can recommend GO Proposals up to its orbit allocation. The panel will also rank order Theory and AR Proposals. In order to encourage the acceptance of larger GO Proposals, a progressive orbit “subsidy” is allocated to the panels, with orbits in the subsidy coming from outside the direct panel allotment. The algorithm for this “subsidy” has the goal of creating an acceptance rate of Regular GO programs that is approximately independent of size.
The panel recommendations generally do not require further approval of the TAC (
Section 6.1.2) and scientific balance will be determined within each panel rather than by the TAC. The panels do not adjudicate Large GO Programs (100 orbits or more; see
Section 3.2.2), Treasury GO Programs (
Section 3.2.5) or AR Legacy Proposals (
Section 3.4.2), but they will send comments on those proposals to the TAC for their consideration.
Panelists are chosen based on their expertise in one or more of the areas under review by the panel. Each panel spans several scientific categories (as defined in
Section 8.8). In Cycle 20, we anticipate having two panels dealing with
Planets and Star Formation (including the Solar System, exoplanets, and planet formation); three panels dealing with
Stars (of any temperature and in any evolutionary state); two panels dealing with
Stellar Populations (and Galactic ISM); three panels dealing with
Galaxies (including unresolved stellar populations, ISM in external galaxies, galaxy morphology, and galaxy evolution); two panels dealing with
AGN and IGM (including quasar absorption lines); and two panels dealing with
Cosmology (including large-scale structure, gravitational lensing, and galaxy groups and clusters). Within a panel, proposals are assigned to individual expert reviewers based on the keywords given in the proposal (see
Section 8.9). These keywords should therefore be chosen with care.
The TAC will include the TAC chair, the panel chairs, and three at-large members to ensure broad expertise across the full range of scientific categories. The primary responsibility of the TAC is to review the Large GO Programs (100 orbits or more; see
Section 3.2.2), including Treasury GO Programs (
Section 3.2.5), AR Legacy Proposals (
Section 3.4.2), and any other particularly large requests of resources (GO Calibration programs, SNAP, AR, Theory or Pure Parallel). The HST TAC will also rank accepted Pure Parallel programs, and is the arbiter of any extraordinary or cross-panel issues.
