9.2 Description of the Observations

(This item is required only for GO and SNAP proposals)

This section of the PDF file should be used to provide a short description of the proposed observations. All HST observations in Cycle 16 will be undertaken in the Two-Gyro Science Mode that has been developed by the HST project. The principal change with respect to Three-Gyro Mode, the standard in cycles prior to Cycle 15, is reduced scheduling flexibility (fewer orbits available for a given target). Image quality is virtually indistinguishable from that in Three-Gyro Mode; observers should expect nearly identical scientific performance in Two-Gyro Mode, albeit at the reduced scheduling efficiency noted above. Further details are given in the HST Two-Gyro Science Handbook.

The description of the proposed observations should explain the amount of exposure time and number of orbits requested (e.g., number of objects, examples of exposure-time calculations and orbit estimates for some typical observations). You should summarize your target acquisition strategies and durations where relevant. For CVZ targets, state the number of CVZ opportunities available in the cycle.

Discuss and justify any non-standard calibration requirements (see Section 4.3). You should estimate the number of orbits required for these special calibrations, and include them in the OS (see Section 8.15).

Depending on the type of proposal, the following items should also be included:

• Survey proposals should state explicitly the number of orbits required for each visit to a target. If the program targets require visits of different duration, the proposer should explain how the total number of orbits requested was estimated.
• Long-term projects should provide summary information for the entire project, along with a cycle-by-cycle breakdown of the requested spacecraft orbits.
• Treasury Programs should discuss the data products that will be made available to the community, the method of dissemination, and a realistic time line. It is a requirement that data products be delivered to STScI in suitable digital formats for further dissemination via the HST Data Archive or related channels. Any required technical support from STScI and associated costs should be described in detail.
• Proposers submitting Large, Coordinated HST-Spitzer and Treasury Programs should discuss how they have designed their program with regard to schedulability.
  • All proposers should include the number and durations of the schedulability windows for each observation.
  • Proposers of programs with timing constraints and timing relationships between observations should describe those constraints, including allowable flexibility.
  • Proposers of programs containing large blocks of orbits at constrained orientation angles, such as mosaics and surveys, should describe those constraints and allowable flexibility.
  • Proposers requesting large blocks of orbits with a single target should estimate how many orbits/day will be required for their programs, during the scheduling windows that meet their timing and orientation restrictions.
  • If a target visibility other than that indicated on the Large Program Web page is used, state the value used and explain why you used that value.
• Calibration Proposals should present a detailed justification of how they will achieve the goals of the program, and if applicable, a description of the conditions under which these goals will be achieved.
• Calibration Proposals should discuss what documentation, and data products and/or software will be made available to STScI to support future observing programs