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SV Call for Proposals

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The Gemini Multi-Conjugate Adaptive Optics System (GeMS) and the Gemini South Adaptive Optics Imager (GSAOI) commissioning activities started in 2011 and continued during the first semester of 2012. The commissioning is expected to be completed during the 2012B semester. Therefore, we invite the Gemini community to propose System Verification (SV) programs for GeMS/GSAOI. Approximately 60 hours are available in the 2012B semester for this SV call.

Proposal submissions are due FRIDAY, SEPTEMBER 14, 2012, 23:59 UT .

System Verification is the final step of testing prior to general use of the instrument by the Gemini community. It is intended to be "end-to-end" testing, verifying the readiness of the entire system from observation preparation to data reduction (using the Gemini GSAOI IRAF data reduction package). It is also intended to exercise the instrument with a variety of observing programs and demonstrate to the community, through interesting and challenging science programs, the unique capabilities of GeMS and GSAOI on Gemini South.

SV proposals will be evaluated by the Gemini GeMS/GSAOI Science Team with input from the Gemini Science and Technology Advisory Committee. Recommended programs will be forwarded to the Gemini Director for approval. The SV team will assist PIs in completing Phase II. Selection of SV programs will be done to ensure a wide range of types of target and observation. The different types of targets and approximate allocation times are given below. The allocated hours are notional only and will vary based on the programs selected. The proposed target observations must use the filters that are currently installed on GSAOI.

Type of target and approximate allocation times
Type of target Allocated time
Bright point Sources < 5 hours
Crowded fields 10 hours
Extended sources (i.e. targets that mostly fill the GSAOI field of view) 15 hours
Faint sources (stars or extended sources) 25 hours
Non-sidereal(1) < 5 hours

(1) Observations of non-sidereal targets have not been fully tested. The commissioning team has successfully guided 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. It is anticipated that very few non-sidereal targets will be selected.

SV teams will be responsible for providing written, in-depth assessments of SV observations within two months of data acquisition. The data obtained during SV will be made available to the international Gemini community after a two-month proprietary period, and the assessments of the SV teams will be published on the Gemini web pages. Community participation will help to ensure that GeMS and GSAOI are a success when the system is in regular use.

GSAOI is a near-infrared adaptive optics camera used in conjunction with the GeMS. GeMS/GSAOI provides near diffraction limited images in the 0.9 - 2.4 µm wavelength range. The GSAOI imager detector is formed by 2 x 2 mosaic Rockwell HAWAII-2RG 2048 x 2048 arrays. Located at the f/32 GeMS output focus, GSAOI records images in a 85" x 85" field-of-view with an imaging scale of 0.02"/pixel and a gap between the arrays of ~ 3". See the GeMS and GSAOI web page for more detailed information. The GSAOI Integration Time Calculator is available to estimate the required exposure times.


1. Target visibility: We expect to observe SV programs between December 1, 2012 and January 31, 2013. Therefore the targets should have RAs between 01 hour and 12 hours and Declinations between +10 degrees and -70 degrees (elevation > 45 degrees).

2. Guide stars: GeMS requires 3 optical natural guide stars for tip-tilt wave front sensing (called CANOPUS wave front sensor, CWFS) and 1 GSAOI NIR On-Detector Guide Window (ODGW) to compensate for flexure. The applicants must consider the following guide star constraints (see Guiding Options for details):

  • Limiting magnitudes for CANOPUS optical guide stars of R < 15.5 mag.
  • Limiting magnitude for GSAOI ODGW guide star of H < 14 mag (can be the same star as one of the CANOPUS guide stars).
  • Guide stars cannot be extended objects (e.g. galaxy core).
  • 3 CANOPUS optical natural guide stars plus one infrared GSAOI ODGW are required.

3. Observing conditions constraints: The following constraints are allowed:

  • Image Quality(2): 20%-ile, 70%-ile or 85%-ile.
  • Sky Transparency (cloud cover): photometric (50%-ile).
  • Sky Background: Any.
  • Sky Transparency (Water vapor content): Any.

(2) Reasonable corrections are possible under poorer image quality conditions (up to 1" natural seeing or IQ=85%-ile). Proposers that do not require diffraction-limited images are encouraged to submit targets for these conditions. Details about the image quality and Strehl ratios that could be achieved with GeMS for different seeing conditions can be found in the Performance and limiting magnitude web page.


To submit a program, use the 2013A Phase I tool and include observing constraints, target lists, and GSAOI filter configuration information. Be sure to select "Other Proposal Types" and "System Verification" in the Proposal Class and the Proposal Type fields respectively, inside the Scheduling and Time Request section of the Phase I Tool.

The Phase I tool provides a percentage for the likelihood of finding a suitable guide stars for GeMS/GSAOI (i.e. the percentage indicates whether a guide star is available or not). The Phase I tool does not provide information about the spatial distribution of the guide stars ("asterisms") or information about the Strehl ratio (required as an input parameter in the GSAOI ITC). Therefore, PIs must use the Gemini Observing Tool (OT) to verify the feasibility of CANOPUS WFS and GSAOI ODGW guide stars. Detailed information about how to setup the guide stars in the OT can be found in the GSAOI OT Details web page. The overheads associated with a GeMS/GSAOI science observation can be estimated using the information given in the Overheads web page.


  • Include a picture of the OT position editor with target field, the CANOPUS/GSAOI FOV and the selected CWFS and ODGW stars in the Technical Justification of the proposal.
  • Include the magnitudes of the CWFS guide stars in R and the magnitude of the ODGW in H in the Technical Justification of the proposal.

Scientific justification must be less than 1000 words. The technical justification should be sufficiently complete within its 1000 word limit that program feasibility can be assessed easily. A statement of data reduction plans must also be included in the technical justification. Proposers may use other data reduction tools in addition to the GSAOI package. Selection for SV is based in part on the ability of the proposers to reduce the data and return feedback within a reasonable time.

By submitting an SV program the proposers agree to the following:

  • There is no guarantee that the program will be observed.
  • The proprietary period for SV data is two months.
  • The PI will provide reduced data to Gemini for public release within two months of the completion SV program.

The GeMS/GSAOI astronomers will assist PIs of the successfully accepted programs to complete the Phase II.


August 27 Call for SV proposals
September 14 Phase I deadline
October 12 Announcement of selected programs
November 6 Phase II deadline
November 28 Start of Commissioning/SV run

Please, feel free to contact us with questions.


The GeMS/GSAOI team

Contacts: Rodrigo Carrasco ( and Benoit Neichel (

Gemini Observatory Participants