Spacecraft Orbits and Continuous Viewing Zones (CVZ)
HST observing time is allocated in (integer) numbers of spacecraft orbits. Both primary and
parallel orbits may be allocated. Observations that require a HST pointing at a specific
astronomical object are done during primary orbits. Observations that can be made with a
second instrument during a primary pointing, typically for survey programs, are allocated
Programs can increase their observing efficiency (i.e., require a smaller total number of orbits)
by specifying observations to be obtained in the HST's Continuous Viewing Zones (CVZs). These are
the regions of the sky in which it is possible to view a target for several orbits without interruption
by Earth occultations (see Section 4.1.1 of the CP). Proposers have been instructed to request CVZ
observations for those targets for which it is in principle technically feasible to schedule such
observations (in practice not all such observations will turn out to be schedulable in the CVZ, and
will be done instead using the regular, non-CVZ orbital visibility).
For many proposals, routinely available instrument calibrations will be sufficient. However,
some proposals may also have special calibration requirements (as identified by the proposer).
Observing time required for such special calibrations should be explicitly included in the
requested resources (i.e., extra orbits). If you have any questions about the calibration
requirements for a proposal, please contact Jennifer Mack:
firstname.lastname@example.org (before the meeting) or request the opinion of a technical expert (during
Data Rights and Proprietary Period
GOs and GTOs have exclusive access to their scientific data during a proprietary period that
is normally 12 months. However, proposers have the option to request a proprietary period shorter
than one year, (i.e., 3, or 6 months) or to waive their proprietary rights altogether.
Particularly in the case of snapshot or pure parallel programs, reviewers may take this into
account in evaluating the benefits of the proposal, because of the potential use to the community
at large. Data taken under the Treasury program will generally have no proprietary period, although
brief proprietary periods may be requested if they will enhance the public data value.
HST observations may not duplicate other observations already obtained with HST, or observations
that are currently in the pool of already accepted HST programs, unless clearly justified in the
Justify Duplications Section (e.g., because of variability). An observation is defined as duplicating
a previous one if it is on the same astronomical target or field, with the same or similar instrument,
a similar instrument mode, similar signal-to-noise, similar spectral resolution, and a similar spectral
range. It is the responsibility of proposers to check their proposed observations against the catalog
of previously executed or accepted programs. Systematic computer-aided duplication checks of the proposal
pool are not performed in Phase I. Such checks will be carried out on the approved pool following Phase
II submissions. Any adjustments required by policy will be made at that time (typically, few actual
duplications are found at that point). If a proposer wants to perform an observation that is technically
a duplication, it must be flagged in the observation summary and explained in the Justify Duplications
section. Such observations will only be done if they are explicitly approved by the Panels and TAC,
otherwise they will be disallowed in Phase II. There are special protections in place for duplication
of GTO observations. All policies on duplications are described in detail in Section 5.2 of the CP.
We request that during the review, Panels alert us to any actual or perceived duplications that are not
flagged. A case that occurs often in practice is that of different proposals in the same cycle requesting
observations that would be considered duplications of each other. If such cases are identified within a
Panel, then the Panel should generally recommend that the duplicate exposures be dropped from the
lower-ranked proposal(s). Merging of separate proposals is not allowed. Also, allocation of the same
data to more than one program is never a viable option, due to the substantial policy and technical
Two proposals to do identical science on different targets do not constitute a duplication. However,
it may or may not be a prudent use of HST time, so Panels may decide to recommend only the program
with the higher scientific merit or if the scientific problem is deemed of sufficient importance and
the competing proposals are of comparable merit, to approve both of them.
Proposers that duplicate targets and/or science may well be sent to different panels. Because
fewer than 1 in 6 proposals will be approved, cross-panel duplications should be considered only after the
first run-through by each panel. The chairs should compare lists of highly ranked proposals and
identify possible overlapping (successful) proposals. The Chairs should compare the proposals in
question, consulting the panel as necessary. Both could be approved or only one, depending on the
panels' judgment as to the importance of the science. If necessary, each panel can read the other's
proposal. If the panels do not agree on the disposition of duplicating proposals, then the final
recommendation will be made by the TAC.
The allocation of observing time recommended by the Panels and TAC is to be made on the basis of
scientific merit without regard to the nationalities of the proposers. An agreement between NASA
and the European Space Agency states that a minimum of 15% of the HST observing time, on average,
over the lifetime of the HST project, will be allocated to Principal Investigators from ESA member
state institutions. This requirement has always been met through the normal competitive peer review,
so it is not necessary to track the ESA allocation explicitly during the Panel and TAC deliberations.