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Visiting Instrument Program

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The following policy was developed in discussion with the Gemini Science and Technology Advisory Committee (STAC) and Gemini Board of Directors; it describes the principles on which a visiting instrument may be accommodated and used, and describes the process by which the PI of an instrument team may seek access for their instrument. It was initially approved by the Board at its November 2012 meeting, and subsequent updates were endorsed in 2017/8.

You can also look at the Visiting Instrument Telescope Interfaces.

Program Description

Gemini Observatory has a strong commitment to meeting our community’s instrumentation needs.  One of the ways we can accomplish this is to offer PIs the opportunity to use their own instruments, usually with minimal support from Gemini engineering and operations staff. With the help of the instrument teams, these instruments can often be made available to the larger user community as well. In recent years, some of these Visiting Instruments have been much sought after, comprising a significant fraction of Gemini usage at both telescopes.

The guiding principles and practical information regarding this program can be found here, and in addition, interested parties are encouraged to seek more information by emailing the Gemini Visiting Instrument Program Manager, Hwihyun Kim, at  We are able to host a broad range of instruments, large and small, encompassing diverse capabilities, and we will be more than happy to discuss new possibilities with you.  For PIs wishing to use existing Visiting Instruments for their science, please check the list of instruments in the current call for proposals and remember to keep checking back, as new capabilities are added frequently!


  1. Visiting Instruments (VIs) must be scientifically productive; hence observing runs are normally allocated time by the National Time Allocation Committee (TAC)/International TAC process. Where performance needs to be determined via a short run prior to wider offering, either (i) a small amount of Director’s Discretionary time may be requested or (ii) the STAC may ask the Observatory to remove a sufficient block of time from the normal schedule.
  2. Support of visiting instruments is subject to Gemini staff availability.
  3. VIs whose support requires a major effort on the part of Gemini staff, or which are expected to visit multiple times, must be offered to the Gemini user community. Instruments which can be accommodated without much effort may be used for a PI's own program only. PIs may invite collaborations and may invite Gemini staff onto their team.
  4. No visiting instrument is expected to be offered to the community on its first visit. The first visit may constitute an observing run allocated to the PI through the TAC, or a commissioning run using an allocation of Director’s Discretionary or Engineering time.
  5. Visiting Instrument observing runs, for PI science and for community access, are normally scheduled in blocks and are carried out by the visiting instrument team.
  6. If an instrument appears to offer a popular capability and demonstrates competitive performance, the observatory will normally pursue an agreement with the VI team to offer the instrument in the Call for Proposals.  In the unlucky event that the VI team submit telescope proposals that are not accepted by the TAC, but other proposals are, the VI team are still expected to support community observations and may choose to request special dispensation via Director’s Discretionary Time.
  7. Full integration of a VI which will see limited use is not possible. If full integration is required, a longterm commitment must be expected and the PI should follow the guidelines associated with conversion to a “resident” or Facility Instrument.  These will be online soon, but in the meantime, more information can be obtained by emailing
  8. As Gemini is funded via the United States National Science Foundation, all data taken using VIs must be made available to the community following the standard proprietary period. Access should be via the Gemini Observatory Archive (GOA), but accommodations can be made if this is not feasible.  If the Visiting Instrument is to be offered to the community, the method via which the community will access their data must be agreed before any run takes place.
  9. Visiting Instruments will not be provided for in the Gemini data reduction package or Quality Assessment (QA) pipeline. However, a condition of any visit with external PI involvement is that the visiting team undertakes either (i) to reduce all data and provide reduced products to the PIs and GOA or (ii) provide a pipeline that is compatible with DRAGONS, the upcoming Gemini data reduction suite.
  10. Unless impractical due to the specialized nature of the instrument, data files made available to the community will be in multi-extension FITS format. Header information must be appropriate for later "archival" use. The Gemini Visiting Instrument Interface is available to enable headers to include accurate values for keywords such as telescope position, timing etc.
  11. Visiting instrument runs can be interrupted by rapid Targets of Opportunity (ToOs), provided that Gemini staff can carry out the ToO observation and the instrument switch can be carried out efficiently enough. Other priority decisions may be needed if large amounts of telescope time are allocated to a VI.  In all cases, final decisions lie with the Head of Science Operations.
  12. Visiting instrument PIs agree to follow Gemini safety policies and will not put people or facilities at risk.​

How to Apply

For an instrument which may be expected to require a small amount of effort or money, the following process should be followed:

  1. Before a first visit, the PI consults the Visiting Instrument Telescope Interfaces page, and engages with Gemini staff ( to discuss possibilities.  The first things to consider are time frame, the scope of work required to support a visit, and the goals of the team at Gemini (PI science, supporting community observations, etc). The following points assume that the effort is confirmed to be small (e.g. an installation day and removal/packing day for the site crew, minimal software and cabling, limited night support etc.).
  2. The PI then submits a proposal to the Gemini observatory detailing their plans and goals, what resources they expect to need, and a brief description of the instrument with a sample science case.  This proposal need only be a couple of pages, and the Gemini VI Program manager is available to provide guidance.
  3. Following this, the VI team submit a proposal to their own partner TAC to support a visiting-instrument run, stating in the technical justification the outcome of the consultation with Gemini staff.  If the TAC awards time, the run is accommodated.
  4. If the VI team choose to support community observations, the instrument will be included in the Call for Proposals following successful commissioning and/or PI science with the instrument on Gemini, and the submission of a commissioning report. Requirements or additional effort needed to make the instrument available to the community and to support any community time allocated will be discussed at this point.
  5. If in the course of the visit, the work required grows significantly above the anticipated level, Gemini staff will make a best-efforts attempt to ensure the success of the run but the Observatory retains the right to cancel it.

If, in the course of steps 1 and 2 above, it is determined that supporting the VI will require more than the usual time or resources, the following additional steps apply:

  1. The STAC is presented with the proposal containing at least the following summary information: (i) the capabilities of the instrument,  (ii) the effort estimate  and (iii) a statement of the range of possible science that the instrument could support. The Observatory also presents a statement of what other work might be adversely affected to accommodate the VI. The STAC is invited to weigh the effort required against other priorities, and to determine (i) whether to proceed, (ii) if so whether the instrument should be formally offered to the community at a subsequent visit (subject to performance being demonstrated in the first) and (iii) whether the PI should apply via the normal TAC process or the Observatory should block time off the normal schedule, for a PI-only run to enable performance to be determined with a view to future wider offering.
  2. The STAC makes a recommendation to the Board.  The STAC and Board meetings occur semiannually in May and November. If there is a compelling reason to assess the instrument outside of the normally scheduled meetings, this may be possible, but in general, PIs should endeavor to allow enough lead time to have proposals reviewed during the time allocated to this at the normal meetings.

If a VI team and the Observatory feel that a visit longer than 2 semesters (or even an indefinite stay) is warranted, then it may be advantageous to consider integrating the instrument more fully to Gemini software and to consider other means of supporting the observations than with VI team site visits.   This level of integration is considered unusual, and PIs who wish to find out more about this process should contact with any questions.  More information about transitioning to a “resident” or Facility Instrument will be online here soon.

You can also look at the Visiting Instrument Telescope Interfaces.

Visiting Instruments and Large/Long Programs

It is acceptable, and even encouraged, for the PI of a visiting instrument to propose to use it for a Large or Long Program. Consistent with the principles above, the instrument would first need to be confirmed as supportable by the Observatory, and in most cases, have gained time via the normal TAC process for an exploratory initial run. If the initial run is successful, a proposal would be made to the LLP TAC. That proposal would need to be supported with a statement from the observatory that the instrument itself, and the required regular visits, can be accommodated. As a large/long program may require extended visits to be productive, it is not a requirement that the instrument be made available for community access, however open access is strongly encouraged, particularly in the case where the LLP has conditions or requirements that would mean that it might only be observed for a fraction of the duration of any given visiting run. All other aspects of the policy (data archiving etc.) are as stated above.

Currently visiting Instruments

Gemini North:

    • TEXES, the Texas Echelon Cross Echelle Spectrograph is a high resolution (R ~ 4,000-100,000) mid-infrared (4.5-25 micron) spectrometer.  TEXES is offered in the 2024B Call for Proposals. 
    • 'Alopeke (Hawaiian for "fox") is a fast low-noise dual-channel and dual-plate-scale imager based on the Differential Speckle Survey Instrument.  This is permanently mounted on the calibration port at Gemini North.  The Gemini contact scientist for 'Alopeke is Andrew Stephens, and questions may also be directed to gemini-vip (at)
    • POLISH2 is a high-precision polarimeter aimed at exoplanet reflection polarimetry.  POLISH2 was available for 2020B and 2021A.  Questions about POLISH2 observing should be directed to Sloane Wiktorowicz (sloane.j.wiktorowicz (at)
  • HIPPI-2
    • HIPPI-2 is a high-precision polarimeter designed to capture the polarization signatures of exoplanets.  HIPPI-2 is not available yet.
  • MAROON-X  
    • MAROON-X is a fiber-fed, red-optical, high-precision radial-velocity spectrograph expected to have the capability to detect Earth-size planets in the habitable zones of mid- to late-M dwarfs using the radial velocity method.  MAROON-X  has been delivered to Gemini North and used since 2020B.  The Gemini contact scientist for MAROON-X is Siyi Xu, and the PI is Jacob Bean.  Questions may also be directed to gemini-vip (at)

Gemini South:

  • Zorro
    • Zorro (Spanish for "fox") is a fast low-noise dual-channel and dual-plate-scale imager based on the Differential Speckle Survey Instrument (DSSI).  It is permanently mounted on the calibration port at Gemini South. The Gemini contact scientist for Zorro is Jeong-Eun Heo, and questions may also be directed to gemini-vip (at)

Retired Visiting Instruments

    • A high-resolution (R~45,000), single-setting, near IR (1.45 - 2.5 microns) echelle spectrometer.  IGRINS was available from 2020A until 2024A.  The Gemini contact scientists for IGRINS is Aleksandar Cikota, and questions may also be directed to gemini-vip (at)
    • A high-resolution (R ~50,000 - 80,000), near IR (1-5 micron) echelle spectrometer.    Phoenix was in frequent use at Gemini South until 2019, and publications using Phoenix can be searched here.
Visiting Instrument Program | Gemini Observatory


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