New and Important Features with HST in Cycle 17
Proposers should assume that HST will operate in three-gyro mode in Cycle 17.
HST has been operating in two-gyro mode since 29 August 2005.
Servicing Mission 4
- The next servicing mission, Servicing Mission 4 is currently scheduled for August 2008.
Space Shuttle astronauts will install two new instruments, Wide Field Camera 3 (WFC3)
and the Cosmic Origins Spectrograph (COS), together with a new set of gyros and other
flight hardware. WFC3 will replace Wide Field Planetary Camera 2 (WFPC2) as the on-axis
instrument; COS will replace COSTAR. The Space Telescope Imaging Spectrograph (STIS)
suffered a serious electronics failure in August 2004, and the electronics powering
the Advanced Camera for Surveys Wide Field Camera (ACS/WFC) and the High Resolution
Camera (ACS/HRC) failed in January 2007. The ACS Solar Blind Channel (ACS/SBC) is
operating nominally. Hardware and procedures are being developed and tested for potential
repairs to both STIS and ACS.
- Cycle 17 observations will commence after an initial period of instrumental
calibration following the completion of SM4. Cycle 17 will end on 31 December
2009, and Cycle 18 will extend from 1 January to 31 December 2010. With the
change in cycle boundaries, we anticipate moving the Cycle 18 proposal deadline
to July 2009, with the Cycle 18 TAC meeting in September that year. The exact
schedule will be set at a later date.
- We will accept proposals for the following instruments in Cycle 17: all three cameras
on ACS, the ACS/WFC, the ACS/HRC and the ACS/SBC; COS; the Fine Guidance Sensors (FGS);
the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS); STIS; and WFC3.
- Proposers to Cycle 17 should be aware that the instrument complement offered may be
subject to change. Please consult the Cycle 17 Announcement Web Page for up to date
information on the status of HST instrumentation.
- The proposed refurbishments to STIS and ACS will be made on a best effort basis.
Proposals to use one or both of those instruments, in either prime or parallel
mode, must discuss the consequences should the repair prove unsuccessful. The
description should be given in the Special Requirements section of the pdf attachment.
It should discuss the impact on the science and, if appropriate, provide an alternative
observing plan, identifying any changes in either the scope of the observations or
the required resources.
- Unexecuted proposals for STIS and ACS from previous cycles will not be revived for
Cycle 17. With changes in the scientific landscape, and the availability of new
instrumentation on HST, even accepted programs from previous cycles may be regarded
as less compelling in the current environment. Proposers may resubmit such proposals
for independent consideration by the Cycle 17 Telescope Allocation Committee.
- The COS Science team has been allocated 555 orbits for Guaranteed Time Observations.
(Four orbits have already been expended on observations with ACS.) GTO programs are
protected against duplication by General Observers (GOs). Individual observations can be checked for GTO
duplications using tools provided by the HST Data Archive.
COS GTO data have a 12 month proprietary period. A summary of the GTO programs
that will be implemented in Cycle 17 can be found at:
http://www.stsci.edu/hst/proposing/docs/COS-GTO.
- The WFC3 Science Oversight Committee has been allocated 214 orbits of Directors
Discretionary time to carry out an Early Release Science (ERS) program, "Star
formation, near and far". The observations are protected against duplication.
However, the data are non-proprietary, and GOs can propose supplementary
observational programs that build on the WFC3 ERS observations. A summary
of the WFC3 ERS program can by found at:
http://www.stsci.edu/hst/proposing/docs/WFC3-ERS.
- The category of Survey Proposal will continue to be available in Cycle 17. Survey
proposals are like SNAPSHOT proposals in that they allow a large pool of candidate
targets to be specified from which a subset will be selected for execution. However,
Survey proposals are GO programs, and will be ranked against Regular GO programs
in peer review. If selected, a Survey program will be assigned a guaranteed number
of orbits. Therefore, while specific targets are not guaranteed, Survey proposals are
appropriate where it can be demonstrated that a fixed number of targets must be observed
to accomplish the science goals of the proposal. Survey programs must target sources
distributed over a wide range of Right Ascensions (> 12 hours). The observations cannot
require special scheduling constraints (e.g., CVZ, timing requirements, or telescope
orientation requirements), and, to enhance scheduling efficiency, are limited to durations
of less than 48 minutes per orbit. Survey proposals are subsidized at a higher rate than
other GO proposals in the time assignment process.
- Given the uncertainly in the length of Spitzer's Cycle-5, the final cryogenic observing
cycle, the Great Observatories are not including Cycle-5 Spitzer observations in the 2008
joint proposal programs. We expect that joint Spitzer observing opportunities will be offered
in future calls if the Spitzer warm mission is approved.
- The HST pointing control system and the HST scheduling systems were not designed to support
observations of objects as close as the Moon. Nonetheless, observations are possible under
gyro control in three-gyro mode. Planning and scheduling such observations place strong
demands on the available resources. Consequently, while GO proposals to observe the Moon
can be submitted for consideration by the Cycle 17 TAC, these proposals must use observing
strategies that have been used in previous HST lunar observing programs (see the
Lunar Observations User Information Report).
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