Chapter 2:
Special Considerations
for Cycle 17

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In this chapter . . .

2.1 ACS Repair During SM4 / 6 2.2 Dithering in Cycle 17 / 6

Three-Gyro Guilding

We anticipate that all HST observations in Cycle 17 will be undertaken in the Three-Gyro Science Mode, providing greater scheduling flexibil- ity and greater sky coverage (at any epoch) than in Cycles 14, 15 and 16.þProposers should plan their observations accordingly, using the Tar- get Availability Table in the Primer (Table 6.1) and the visibility tools on the HST Phase I Proposal Roadmap Web site.