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What to expect once your observations are in the queue

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Your proposal was accepted, your observations have been defined, checked and set to "ready", and your program is now available for scheduling. What should you expect next? This page outlines what happens once your observations are in the queue, how to monitor their progress, and what to do if things aren't going as you expected.



Queue planning and nighttime operations

Every day a plan is made for the night's observing, with variations for different sets of weather conditions. The queue planning follows a set of principles aimed at making sure that programs are completed and telescope time used efficiently. More detail is given on this page, along with a description of a typical night's observing.

Monitoring your observations

If desired, the progress of a Gemini observing program can be monitored quite closely. There are several ways of doing so:


  • By default, PIs are signed up to receive automatic email notification the morning after each night that data are obtained for a given program. These emails are sent before any quality assessment is performed on the data.
  • The Gemini Science Archive can be queried for data sets belonging to a program. Raw files usually go into the archive shortly after being written to disk (see this page for more details).
  • The archive also sends periodic emails notifying PIs that data sets are available for collection. No sign-up is needed for these emails. These emails go out once Gemini staff have created a data package for the program, usually on Friday of each week for programs with data obtained during the preceding week.
  • The PI (or, in fact, anyone with the program "key") can fetch the program and see how it is progressing. As observations are executed, their status changes in the OT, time is charged to the program and/or partner country, and an "observation log" is created inside each observation. An example of a program with observations in progress can be found here.
  • Various pages in the Queue and Schedules section of the website give program execution statistics. See for instance the "Queue Summary", "Execution Log" and "Database Snapshots" links.


You thought you'd have (more) data by now. What's going on?

We make every effort to obtain as much data as possible of as high a standard as possible. After all, everybody benefits when a good publication is written based on a Gemini data set. However, sometimes programs aren't started, aren't completed, or take longer to complete than the PI anticipated. Recent improvements to the software used by the ITAC to create the queue for the semester mean that the available programs are now more balanced in terms of observing condition requirements and RA distribution, but (for example) a long period of poor weather coinciding with an instrument being on the telescope for a limited time can have a large effect on program execution nonetheless. Similarly, the queue scheduling software is quite effective in ensuring that time-critical programs are observed as requested by the PI, but mistakes and misunderstandings can still occur. If you are concerned about progress on your program, you are welcome to contact your NGO support, Gemini contact scientists or the Head of Science Operations at the relevant site (contact details on this page).

The following information may be useful:


  • Band 1 programs with rollover status will automatically stay active for three semesters (e.g., an 11B rollover program will be available for scheduling through the 12B semester).
  • Semester boundaries are treated as flexible at both sites. To make best use of telescope time, we will start a new semester's observations before the start of that semester, and "balance" that by keeping some (non-rollover) programs active after the end of the current semester.
  • Non-rollover programs not used for this balancing time are deactivated shortly after the end of the semester. Occasionally, programs from previous semesters may be reactivated to fill gaps in the queue. This is unusual, however.
  • Band 3 programs overfill the queue and not all of them will be started. See this page for advice on maximising the likelihood of getting data for your band 3 program, such as choosing a GMOS grating that is commonly in the instrument or relaxing your observing condition constraints. This information may also be useful for PIs of higher- ranked programs in semesters with high weather loss, for example.
  • It is possible to make changes to your program once the semester has started, as long as this does not substantially alter the science approved by the TAC. Certain changes, such as target swaps or improvements to observing conditions, require approval from the local head of science operations. However, if you wish to relax the IQ constraint for your program in order to increase the chances of getting data, for instance, this can normally be easily accommodated. The people mentioned above will be happy to advise.


Data checking, quality assessment and repeat observations

Until the end of the 2012B semester, all files were checked during the days following the acquisition of the data. Starting in 2013A, the daytime data checking is limited to band 1 observations plus other data sets that may be requested by the queue coordinator. The data checking usually takes place the day after the observations are taken, but can take longer if there's a backlog of data after a long weekend, for example. The data checking is described in more detail here, but it includes making sure that the PI's requested observing condition constraints were met, checking for missed calibrations, and looking for signs of possible instrument or telescope issues that could affect the data. Data quality states are set in the file headers and can also be seen in the OT; see here for an example OT screenshot and more explanation.

If a problem is found, then often a replacement observation will be set up by the queue coordinator and made available to be repeated at the next opportunity (NB this does not apply to band 4 programs). This is generally the case for simple issues such as an IQ70 observation taken under IQ85 conditions, does not require PI interaction, and does not affect the program's chances of being completed. If you see new observations in your program that you didn't put there, this is probably why; look for a yellow note or comments in the OT observation log (see above) for the explanation. For more complex or ambiguous cases the queue coordinator or another staff member may get in touch with the PI to ask for more information about how to proceed. A prompt response to such emails helps ensure that data can be retaken in a timely manner, if that is what is needed.

The aim of the nighttime observer and many other observatory staff is to ensure that PIs receive data that meet their requirements. However, if you feel that this is not the case with your data, please get in touch with your NGO support, Gemini contact scientists or the Head of Science Operations for the site in question. If we are at fault we will endeavour to correct the mistake.

Gemini Observatory Participants