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Notes for Eavesdropping Contacts

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In remote eavesdropping, a Contact person (you) for a given program is contacted at night and takes part in target acquisition and data assessment in real time. This page gives information you will need to know in order to take part in an eavesdropping session.


Summit observing of a queue of high-priority science is intensive and can be intrinsically stressful for the observers. Please be aware of the following points, which seek to ensure that they can do their job:

  • All eavesdropping sessions are done at the discretion of the summit observer. Eavesdropping is defined as added value; not necessary to the successful completion of the observation as specified in the OT. The summit observer has the right to discontinue an eavesdropping session at any point.
  • Similarly, network connection or skype problems in the course of a session may or may not be fixed. The observers often have their hands full. If you get disconnected, try to call back but don't assume that the observer has time to investigate what happened. They will, by definition, carry on with your observation.
  • The summit observer may be a staff scientist or a member of the Science Operations Specialists group. They are trained in the use of the instrument but you should not assume that they are familiar with your science.
  • The summit observer must not be asked for advice on observing technique or data reduction. Such enquiries, along with questions about Phase I and II preparation, should be directed first to your NGO.
  • The summit observer and telescope operator work with observing systems and telescope systems as-is. They are not responsible for the properties or efficiency of these systems. If you, as Eavesdropper, feel moved to critique any aspect of these systems, please do so to the Head of Science Operations during daytime hours. Any attempt to engage the night crew in such discussion will normally result in a swiftly terminated session.
  • The summit observer is empowered to ensure that an eavesdropping session does not interfere with the nightly queue plan. If, for example, the queue plan states that your observation must stop and some defined time in order to get onto a high-priority observation in the queue, they will stop it at that time.
  • If you are not content with any of the above as it pans out in any given eavesdropping session, you should contact the Head of Science Operations. Debates with the summit observer are not permitted.

Summit Observing

Here we give a brief description of the summit observing process.

Two people are typically present at the summit: one runs the telescope, the other runs the science program. Eavesdropping adds you. The observing process you are joining in with is described below; the call you receive will normally have gone out between 15 and 30 minutes before the first of these steps.

  1. Observer loads your program in the OT and selects the observation.
  2. Observer sends the observation to the seqexec which then runs it.
  3. Telescope operator slews to the target, while instrument is automatically configuring (can be a few minutes depending on distance to target).
  4. Telescope operator acquires guide star and sets guiding going (up to six minutes total for steps 1 and 2 combined).
  5. Observer, Telescope Operator and Eavesdropper acquire the target (involves taking an image and using "gacq", and iterative offsetting) (instrument specific, see the instrument overhead pages for details).
  6. Observer starts running the seqexec and thus exposing.
  7. first frame comes in and is displayed on the skype sharing session (Eavesdropper and Observer inspect and confirm continuation).
  8. DHS saves data and the Eavesdropper can pick them up from the FITS server.

Contact Person Actions

Once you receive the call, you will normally do the following:

  1. Wake up (sorry!).
  2. Run skype and a browser on your laptop, ipad or other computer.
  3. In skype, contact "gneavesdrop" or "gseavesdrop" and get a video call going. If this is the first time you have eavesdropped, you will need to ask for gseavesdrop or gneavesdrop to allow itself to be added to your contacts before you'll be able to call.
  4. If you want to assess data in real time: in your browser, connect to the gemini gateway (via which you will access the FITS storage server to get quick access to your data). Instructions for the latter are below.

During the Call

The summit observer will set skype to share the desktop on their machine and display one of the telops workstation screens via it. this is the screen on which they will display the target acquisition. You should be able to see that and comment on the target field as the Observer acquires the target. Once the first data frames come in, you will have two options: either just watch the frames on the skype session, or download them via the gateway session in your browser.

Accessing your Data

The Gemini Observatory Archive is designed to make data available for download within a minute or so of the readout completing, and is now the recommended way to download data during eavesdropping sessions. Data access during eavesdropping is now via the archive the same as regular post observing data access.

Your science data will be proprietary. In order to access proprietary data for your program, you will need to have created an account on the archive and be logged in, and you will also need to have registered your program ID with your archive account. Details of this process are provided here. You are encouraged to do this ahead of time, both so that you don't need to do it in real-time when we've just woken you up and as we're observing your project, and also so you get to see the system ahead of time.

Once logged in, we recommend you put both your program ID and the current UT date in the search form to see your data from tonight. Clicking the "Search" button will update the results. Click the [D] next to a file to download that one file. The [P] gives a jpeg preview of the file if available - the preview for each file may take an extra minute or two to become available, so very recent data may not have a [P] link.


Gemini Observatory Participants