The Gemini Multi-conjugate Adaptive Optics System -GeMS, a facility instrument mounted on the Gemini South telescope, delivers a uniform, near diffraction limited images at near infrared wavelengths (0.95 µm -2.5 µm) over a field of view of 120 . GeMS is the first sodium layer based multi laser guide star adaptive optics system used in astronomy. It uses five laser guide stars distributed on a 60 square constellation to measure for atmospheric distortions and two deformable mirrors to compensate for it. In this paper, the second devoted to describe the GeMS project, we present the commissioning, overall performance and operational scheme of GeMS. Performance of each sub-system is derived from the commissioning results. The typical image quality, expressed in full with half maximum, Strehl ratios and variations over the field delivered by the system are then described. A discussion of the main contributor to performance limitation is carried-out. Finally, overheads and future system upgrades are described.

The Gemini Multi-conjugate adaptive optics System (GeMS) at the Gemini South telescope in Cerro Pachón is the first sodium-based multi-Laser Guide Star (LGS) adaptive optics system. It uses five LGSs and two deformable mirrors to measure and compensate for atmospheric distortions. The GeMS project started in 1999, and saw first light in 2011. It is now in regular operation, producing images close to the diffraction limit in the near infrared, with uniform quality over a field of view of two square arcminutes. The present paper (I) is the first one in a two-paper review of GeMS. It describes the system, explains why and how it was built, discusses the design choices and trade-offs, and presents the main issues encountered during the course of the project. Finally, we briefly present the results of the system first light.

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We present the results from the commissioning of the Gemini South Adaptive Optics Imager (GSAOI). Capable of delivering diffraction limited images in the near-infrared, over an 85 ′′ ×85 ′′ square field-of-view, GSAOI was designed for use with the Gemini Multi-Conjugate Adaptive Optics (GeMS) system in operation at the Gemini South Observatory. The instrument focal plane, covered by an array of four HAWAII-2RG detectors, contains 4080×4080 pixels and has a plate scale of 0.02 ′′ -thus capitalizing on the superb image quality delivered by both the all-refractive optical design of GSAOI and the Gemini South MCAO system. Here, we discuss our preliminary findings from the GSAOI commissioning, concentrating on detector characterization, on-sky performance and system throughput. Further specifics about the Gemini MCAO system can be found in other presentations at this conference. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 04/02/2013 Terms of Use: http://spiedl.org/termsIts delivers a uniform, diffraction limited image quality in the near-infrared (0.9 to 2.5 µm) over a field of view larger than 1 arcmin. The main GeMS sub-systems are the AO bench CANOPUS, the Beam Transfer Optics and Laser. Specifications for GeMS and its sub-systems are described in detail in previous papers. 1-4 Specifics of GeMS commissioning can be found in other presentations at this conference. 5,6 GSAOI is a near-infrared adaptive optics imager and the workhorse instrument to be used with GeMS. It was built by the Research School of Astronomy and Astrophysics (RSAA) of the Australian National University. The GSAOI is located at the f/32 output focus of CANOPUS and can deliver diffraction limited images in the wavelength interval of 0.9 -2.4 µm over a field of view of 85 ′′ ×85 ′′ . The GSAOI detector is formed by four Rockwell HAWAII-2RG arrays, with 2040 × 2040 pixels each, with a pixel scale of 0.02 ′′ on sky. The arrays are mounted in a 2×2 mosaic that create a 4080×4080 pixel focal plane with a gap of ∼2.5 ′′ (∼2 mm) between arrays. The instrument is equipped with a set of broad-and narrow-band filters, a pupil imager to set the instrument alignment and defocus lenses to null the non-common-path phase errors between CANOPUS and GSAOI.

With two to three deformable mirrors, three Natural Guide Stars (NGS) and five sodium Laser Guide Stars (LGS), the Gemini Multi-Conjugate Adaptive Optics System (Gemini MCAO a.k.a. GeMS) will be the first facility-class MCAO capability to be offered for regular science observations starting in 2013A. The engineering and science commissioning phase of the project was kicked off in January 2011 when the Gemini South Laser Guide Star Facility (GS LGSF) propagated its 50W laser above the summit of Cerro Pachón, Chile. GeMS commissioning has proceeded throughout 2011 and the first half of 2012 at a pace of one 6-to 10-night run per month with a 5-month pause during the 2011 Chilean winter. This paper focuses on the LGSF-side of the project and provides an overview of the LGSF system and subsystems, their top-level specifications, design, integration with the telescope, and performance throughout commissioning and beyond. Subsystems of the GS LGSF include: (i) a diode-pumped solid-state 1.06+1.32 micron sum-frequency laser capable of producing over 50W of output power at the sodium wavelength (589nm); (ii) Beam Transfer Optics (BTO) that transport the 50W beam up the telescope, split the beam five-ways and configure the five 10W beams for projection by the Laser Launch Telescope (LLT) located behind the Gemini South 8m telescope secondary mirror; and (iii) a variety of safety systems to ensure safe laser operations for observatory personnel and equipment, neighbor observatories, as well as passing aircrafts and satellites.