complete CCAT, augment the core research program, and collaborate on ACTA. The timescale for starting to operate GSMT is quite uncertain, but this option can also be accommodated toward the end of the decade. As regards the sequencing of LSST and GSMT, in this and the two budget scenarios that follow, it is assumed that LSST would enter the MREFC process as soon as the budgets would allow and that GSMT would follow.
In the event that the realized budget is closer to an extrapolation of the president’s FY2011 budget, that is, between the optimistic budget-doubling and the pessimistic flat-budget scenarios, the order of priority is to phase in the recommended core research program augmentations and the Mid-Scale Innovations Program together and at as fast a rate as the budget will allow, noting that the recommended Gemini augmentation is time-critical. LSST would receive an MREFC start and require NSF-AST operations funding beginning in 2016. NSF-AST sup-