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Call for GeMS+GSAOI community commissioning targets

1. Rationale

The Gemini Multi-Conjugate Adaptive Optics System (GeMS) and Gemini South Adaptive Optics Imager (GSAOI) are presently being commissioned at Gemini South. At present, we expect that the completed end-to-end testing of System Verification (SV) for GeMS+GSAOI will be conducted in late 2012. However, given the unique scientific potential of GeMS and the current interest in this capability, Gemini is offering an opportunity for the community to be involved in defining targets for commissioning. We therefore invite astronomers to submit scientifically interesting targets that may be observed during the April 2012 GeMS and GSAOI engineering runs. The intent is to provide a suite of scientifically useful data that demonstrates the unique capabilities of GeMS with GSAOI and may provide a catalyst for subsequent observing programs. Given that GeMS and GSAOI are still being commissioned, this program is offered as a shared risk opportunity, and any observation should be restricted to moderate exposure times to accommodate the engineering schedule and allow for targets that span a range of science targets to be recovered. Complete data sets that are recorded will be made available to the user community; there will be no proprietary period.

2. Broad Requirements and Constraints

Given the time of the observations (April 2012), targets should have Right Ascension between 09 and 19 hours. Targets should also have declinations between +10 and -70 degrees, in order to have a reasonable airmass.

The observations must use filters that are currently installed in GSAOI. A list of these filters can be found here.


Given the need for three GeMS optical natural guide stars for tip-tilt wave front sensing (TTNGS) within the 2 arcmin diameter of the CANOPUS patrol field area and one GSAOI ODGW (On Detector Guide Window) guide star inside the 85 arcsec x 85 arcsec GSAOI field of view, to compensate for possible flexure drift between CANOPUS and GSAOI, it can be anticipated that targets with highest chances of success will be at low or intermediate Galactic latitudes.

The applicant must consider the following guide star constraints:


  • Limiting magnitudes for CANOPUS optical TTNGS of R < 15.5.
  • GSAOI ODGW magnitude brighter than 14 mag in H (can be the same star as the CANOPUS one).
  • Guide stars should not be an extended object (e.g. galaxy core).
  • A minimum of 2 CANOPUS TTNGS plus one GSAOI ODGW.

The applicants must use the latest Gemini Observing Tool (OT) to explore the feasibility of their suggestions before the submission (see the Installing Observing Tool web page for details). Example observations can be downloaded by fetching the Observing Tool GSAOI library (see the OT Libraries web page for instructions). The potential commissioning targets selected by the GeMS/GSAOI commissioning team for the April runs are listed here. We encourage the applicants to check the list before target submission.

The observations will be interlaced with engineering activities and so total exposure times are limited to 1 hour per target. Please be aware that the amount of commissioning time is limited and so it is likely that no more than one or two targets from any given PI will be observed.

3. Information required for submission

Applicants must be in an institution in a Gemini partner or host country/state.

Applications will consist of submissions to, and should contain:

  • A brief (250 words maximum) statement describing the scientific interest of the proposed targets, and how they would demonstrate GeMS/GSAOI capabilities.
  • The compressed XML exported file from the Observing Tool (use gzip or zip to compress the file). The XML file has to contain the target(s) name(s), the co-ordinates and source brightness information (magnitude, flux, etc), the co-ordinates of the three CANOPUS TTWFS guide star and magnitudes in R, and the co-ordinates of the ODGW guide star and magnitude in H.
  • The list of suggested filters.
  • A brief description of observing strategy (e.g. offset amplitude for dithers, exposure times per filter, etc). Image sensitivity tables for GSAOI can be found here. This table can be used to estimate the exposure time per filter.
  • A brief description of special calibration requirements (e.g. background frames, photometric calibration, etc).

4. Applications deadline

a. For targets to be include in the April 9 - 14, 2012 commissioning block, the deadline is Thursday March 29, 2012 at noon Chile time (GMT-3hours).

b. For targets to be included in the April 26 - 29, 2012 commissioning block, the deadline is Thursday April 12, 2012 at noon Chile time (GMT-3hours).

5. Non-Sidereal targets

This mode of observation has not been fully tested. The commissioning team tried, successfully, to guide on Saturn's moons, but guiding on background stars has not been tested yet. Because of this and the need for multiple guide stars for GeMS, targets that move at a non-sidereal rate pose a special challenge. Given the additional observational overhead required to set up on these targets, it is anticipated that only one or two such targets will be selected for observation. For this initial submission, applicants with non-sidereal targets are asked to prepare an OT submission for midnight (Chilean time) for each night of the commissioning block. The applicants of non-sidereal targets that are selected for observation will be contacted by members of the commissioning team to work out additional details.

6. What happens next

Potential targets will be reviewed by Gemini staff and members of the GeMS/GSAOI commissioning team. A final list of potential targets will be selected based on a wide range of criteria including scientific interest, the ability of the observations to demonstrate GeMS capabilities, feasibility, location on the sky, and the desire to provide a balance in science topics. Targets will only be observed as they can be accommodated by engineering activities, and applicants should not expect to receive detailed feedback on the evaluation of their submissions.

There will be no proprietary period, and data will be released following an assessment of overall quality and the construction of packages containing science images and calibrations. Data will be released in the form of raw science frames with calibrations. These programs are a collaboration of the community and the GeMS/GSAOI commissioning team. Thus, the commissioning team should be invited to participate in any scientific publications that result from the observations. Full contact information for the team will be listed with the resulting data.

Please, feel free to contact us with questions.


The GeMS/GSAOI team

Contact information: Benoit Neichel ( and Rodrigo Carrasco (