Hubble Space Telescope Call for Proposals for Cycle 17

1.2 New and Important Features of 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.

• The next servicing mission, Servicing Mission 4 (SM4; see Appendix B.1.7 of the HST Primer) 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.

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• 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 (see Section 9.3). 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 Time Assignment 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), as described in Section 5.2.1. Individual observations can be checked for GTO duplications using tools provided by the HST Data Archive (See Section 1.4.7). 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 (see Section 5.2.1). 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 (see Section 3.2.3 for full details). 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 (see Section 6.1.1).
• 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).

The following features also deserve special mention, but have not changed since the last cycle:

• STScI experience with scheduling Large and Treasury Programs in Cycles 11 through 16 has shown that some programs can introduce substantial difficulties in developing an effective and efficient long-range observing schedule. Proposers submitting Large and Treasury Programs are asked to include additional technical details (e.g., orient constraints, tiling strategy for large mosaic programs and time constraints) in the "Description of the Observations" section (see Section 9.2) to provide information on the scheduling aspects of their program.
• In addition to the proposal categories that have existed for many cycles, STScI continues to solicit proposals in the categories of `Treasury Proposals' (see Section 3.2.6), `Theory Proposals' (see Section 3.4.4) and `Legacy AR Proposals' (see Section 3.4.2), all of which were started successfully in Cycle 11. Also, it remains possible to request observing time on Chandra (see Section 3.5) and NOAO telescopes (see Section 3.6) in combination with requests for HST observations.