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Assembly of the Queue and Classical Schedule

The draft queue and classical schedule are assembled from the proposals that have been recommended for time by the NTACs. One important concept in bringing together these ranked lists of proposals is that of the merging sequence of which an example is:

[merging sequence]

The merging sequence, of which example from semester 2002A is shown above, is a sequential list of all the Gemini partner countries as well as the host site (University of Hawaii or Chile). Earlier versions of the merge adjusted the frequency with which each partner occurred in the sequence to be proportional to its time available in that semester, after correction for the various 'puts and takes' e.g. imbalance in aggregate usage. Starting in 2008A, the frequency was fixed to the nominal time allocations, and the quota of time awarded on each sampling was adjusted from a default of three hours to a larger or smaller amount, depending on the partner's time imbalance. This ensures correct balance in assembling the queue. The partner's recommended classical time is removed from their total allocation before the queue merge is carried out. Any minor advantage in being the partner with 'first pick' (the US in this case) is reduced by rotating the starting point amongst the partners in subsequent semesters.

The merging sequence includes observing time for the Gemini Staff, effectively as another partner. This is at the discretion of the Gemini Director and depends in part on the assessment of proposals by the staff TAC (see an example sequence assuming 10% staff time).

The merging sequence is cycled through as many time as necessary to use every partner's available queue time. The available time in each observing constraint (e.g. dark time, SB50) is also checked and reduced on each allocation as appropriate; when the time in each bin is used no more programs requiring that condition are merged. Currently, we allow the poorer conditions to be overfilled, but the best image quality, dark and dry time, and photometric time, are not allowed to be overfilled. If a program cannot be scheduled it is skipped.

A simplified worked example of the first few steps of an early version of the merging process can be found in Puxley & Boroson (SPIE...1996; Gemini Preprint #13).