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Completion expectations for queue programs

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Here we give a guide to expectations for the completion of Band 1, 2 and 3 programs. The three bands are best described as (i) top priority, intended to be executed and if possible completed (ii) lower priority, but intended to be executed to some reasonable completion rate and (iii) fillers, which should, in order to get data, be able to take worse observing conditions and be particularly aware of other constraints that may affect their execution.


We fill the queue to a level consistent with the above descriptions in a semester with reasonable weather. In case of a semester with poorer-than-normal conditions or significant instrumental or telescope problems, we attempt to protect programs in Band 1 as best we can (in the sense that any good weather will go to those programs). It is a clear signature of bad weather that Band 3 completions exceed those in the other two bands, and in such cases, programs in Band 2, which still tend to have tight observing conditions requirements, often lose out. The above analysis excludes target of opportunity programs, for which the completion rate depends on the rate of triggers and which we cannot therefore control, and block-scheduled instruments or observing modes, where statistics vary a lot (up and down) due to coincidences between observing blocks and weather.


The figures below show completion statistics in the regular queue, over the period since the commencement of multi-instrument queue observing in 2005. Grey lines represent the ratio of the total usable time in the semester to the total advertised time in the call for proposals (this line has a mean level corresponding to weather loss). The blue histograms represent the fraction of programs achieving a completion rate of 80% or above, and the white dots show the corresponding fraction of programs which achieved a completion rate of 100%. These figures should serve as a guide to what to expect in terms of completion rate. They exclude Target of Opportunity programs, and those executed in "schedule blocks".



Gemini North 

The significant recent feature at Gemini North was the shutter failure of 2013B and 2014A; Band 1 completions were protected against this, but Band 2 suffered badly. 

  • Grey: Ratio of total usable time in the semester to the total advertised time
  • Blue: Fraction of queue programs reaching 80% complete
  • White dots: Fraction of queue programs reaching 100% complete


  • Same as figure above.


  • Same as figure above.


Gemini South 

The significant recent feature at Gemini South has been a combination of weather loss, earthquakes and laser problems in 2015B and 2016A; even Band 1 was not immune to these problems. 


  • Same as figure above.

  • Same as figure above.


  • Same as figure above.


Breakdown: good and bad semesters


As seen above, Gemini North in 2014A presented a particularly bad semester, with shutter failure and weather reducing the amount of available time significantly.  2014B represented a more "average" semester, with good Band 1 completion rate and an understandable distribution between Band 1,2 and 3. Note that in a "reasonable" semester, a good fraction of programs reach 100% completeness.







Gemini Observatory Participants