Gemini Observatory
The Gemini Observatory comprises two 8.1-metre telescopes, Gemini North and Gemini South, situated in Hawaii and Chile, respectively. These twin telescopes offer extensive coverage of the northern and southern skies and rank among the most advanced optical/infrared telescopes available to astronomers. .
The observatory is owned and operated by the National Science Foundation of the United States, the National Research Council of Canada, CONICYT of Chile, MCTI of Brazil, MCTIP of Argentina, and Korea Astronomy and Space Science Institute of Republic of Korea. The NSF is the primary funding contributor, providing about 70% of the required resources. The Association of Universities for Research in Astronomy manages the operations and maintenance of the observatory through a cooperative agreement with the NSF, acting as the Executive Agency on behalf of the international partners. NSF's NOIRLab is the US national center for ground-based, nighttime optical astronomy and operates Gemini as one of its programs.
The Gemini telescopes are equipped with modern instruments and excel in optical and near-infrared performance. They utilize adaptive optics technology to counteract atmospheric blurring. Notably, Gemini leads in wide-field adaptive optics assisted infrared imaging and has recently commissioned the Gemini Planet Imager, enabling researchers to directly observe and study exoplanets with extreme faintness compared to their host stars. Gemini supports research across various domains of modern astronomy, including the Solar System, exoplanets, star formation and evolution, galaxy structure and dynamics, supermassive black holes, distant quasars, and the structure of the Universe on large scales.
Previously, Australia and the United Kingdom were also involved in the Gemini Observatory partnership. However, the UK withdrew its funding at the end of 2012. In response, the observatory has significantly reduced operating costs, streamlined operations, and implemented energy-saving measures at both sites. Additionally, both telescopes are now operated remotely from Base Facility Operations centers located in Hilo, Hawaii, and La Serena, Chile. In 2018, KASI has signed an agreement to become a full participant of the Gemini Observatory.
Overview
The Gemini Observatory's international Headquarters and Northern Operations Center is located in Hilo, Hawaii at the University of Hawaii at Hilo University Park. The Southern Operations Center is located on the Cerro Tololo Inter-American Observatory campus near La Serena, Chile.- The "Gemini North" telescope, officially called the Frederick C. Gillett Gemini Telescope is located on Hawaii's Mauna Kea, along with many other telescopes. That location provides excellent viewing conditions due to the superb atmospheric conditions above the dormant volcano. It saw first light in 1999 and began scientific operations in 2000.
- The "Gemini South" telescope is located at over elevation on a mountain in the Chilean Andes called Cerro Pachón. Very dry air and negligible cloud cover make this another prime telescope location. Gemini South saw first light in 2000.
Both Gemini telescopes employ a range of technologies to provide world-leading performance in optical and near-infrared astronomy, including laser guide stars, adaptive optics, multi conjugate adaptive optics, and multi-object spectroscopy. In addition, very high-quality infrared observations are possible due to the advanced protected silver coating applied to each telescope's mirrors, the small secondary mirrors in use, and the advanced ventilation systems installed at each site.
History
It is estimated that the two telescopes cost approximately US$187 million to construct, and a night on each Gemini telescope is worth tens of thousands of U.S. dollars.The two 8-meter mirror blanks, each weighing over, were fabricated from Corning's Ultra Low Expansion glass. Each blank was constructed by the fusing together of and subsequent sagging of a series of smaller hexagonal pieces. This work was performed at Corning's Canton Plant facility located in upstate New York. The blanks were then transported via ship to REOSC, located south of Paris for final grinding and polishing.
One decision made during design to save money was eliminating the two Nasmyth platforms. This makes instruments like high resolution spectrographs and adaptive optics systems much more difficult to construct, due to the size and mass requirement inherent with Cassegrain instruments. A further challenge in designing large instruments is the requirement to have a specific mass and center-of-mass position to maintain the overall balance of the telescope.
UK funding crisis
In November 2007 it was announced that the UK's Science and Technology Facilities Council had proposed that, to save £4 million annually, it would aim to leave the telescope's operating consortium. At a consortium meeting in January 2008, the conclusion was made that the UK would officially withdraw from the Gemini Partnership and the Gemini Observatory Agreement effective February 28, 2007. This decision significantly disrupted observatory budgets, and resulted in the cancellation of at least one instrument in development at that time, the Precision Radial Velocity Spectrograph.Since the reason for the UK breaking its part of the agreement seemed to be entirely financial, there was public outcry, including the "Save Astronomy" movement which asked citizens to speak up against the astronomy budget cuts. The UK rethought their decision to withdraw from Gemini, and requested reinstatement into the agreement, and were officially welcomed back on February 27, 2008. However, in December 2009 it was announced that the UK would indeed leave the Gemini partnership in 2012, as well as terminating several other international science partnerships, due to continuing funding limitations.
Directorship
The first director of Gemini was Matt Mountain, who after holding the post for eleven years left in September 2005 to become director of the Space Telescope Science Institute. He was succeeded by, who served for nine months, after which time Doug Simons held the directorship from June 2006 to May 2011. He in turn was succeeded by an interim appointment of the then-retired Fred Chaffee, former director of W. M. Keck Observatory. Chaffee was succeeded in August 2012 by Markus Kissler-Patig, who held the post until June 2017. Laura Ferrarese succeeded Kissler-Patig in July 2017 with an interim appointment. Jennifer Lotz took over as the directory on September 6, 2018, but left in 2024 to begin a 5 year appointment as Director of STScI. She was replaced by Scott Dahm as an interim director in January 2024.Governance and oversight
The Observatory is governed by the Gemini Board, as defined by the Gemini International Agreement. The Board sets budgetary policy bounds for the Observatory and carries out broad oversight functions, with advice from a Science and Technology Advisory sub-Committee and a Finance sub-Committee. The U.S. holds six of the 13 voting seats on the Gemini Board. The U.S. members of the Board typically serve three year terms and are recruited and nominated by the National Science Foundation, which represents the US community in all aspects of Gemini operations and development. Gemini is currently managed by the Association of Universities for Research in Astronomy, Inc., on behalf of the partnership through an award from NSF. AURA has operated Gemini since its construction in the 1990s.NSF serves as the Executive Agency and acts on behalf of the international participants. NSF has one seat on the Gemini Board; an additional NSF staff member serves as the Executive Secretary to the board. Programmatic management is the responsibility of an NSF Program Officer. The Program Officer monitors operations and development activities at the Observatory, nominates U.S. scientists to Gemini advisory committees, conducts reviews on behalf of the partnership, and approves funding actions, reports, and contracts.
Instrumentation
Adaptive optics
Both Gemini telescopes employ sophisticated state-of-the-art adaptive optics systems. Gemini-N routinely uses the ALTAIR system, built in Canada, which achieves a 30–45% Strehl ratio on a 22.5-arcsecond-square field and can feed NIRI, NIFS or GNIRS; it can use natural or laser guide stars. In conjunction with NIRI it was responsible for the discovery of HR8799b.At Gemini-S the Gemini Multi-Conjugate Adaptive Optics System may be used with the FLAMINGOS-2 near-infrared imager and spectrometry, or the Gemini South Adaptive Optics Imager, which provides uniform, diffraction-limited image quality to arcminute-scale fields of view. GeMS achieved first light on December 16, 2011. Using a constellation of five laser guide stars, it achieved FWHM of 0.08 arc-seconds in H band over a field of 87 arc-seconds square.
An adaptive secondary mirror has been considered for Gemini, which would provide reasonable adaptive-optics corrections to all instruments on the telescope to which it is attached. However, as of 2017, there are no plans to implement such an upgrade to either telescope.
Instruments
In recent years the Gemini Board has directed the observatory to support only four instruments at each telescope. Because Gemini-N and Gemini-S are essentially identical, the observatory is able to move instruments between the two sites, and does so on a regular basis. Two of the most popular instruments are the Gemini Multi-Object Spectrographs on each of the telescopes. Built in Edinburgh, Scotland by the UK Astronomy Technology Centre, these instruments provide multi-object spectroscopy, long-slit spectroscopy, imaging, and integral field spectroscopy at optical wavelengths. The detectors in each instrument have recently been upgraded with Hamamatsu Photonics devices, which significantly improve performance in the far red part of the optical spectrum.Near-infrared imaging and spectroscopy are provided by the NIRI, NIFS, GNIRS, FLAMINGOS-2, and GSAOI instruments. The availability and detailed descriptions of these instruments is documented on the Gemini Observatory Web site.
One of the most exciting new instruments at Gemini is GPI, the Gemini Planet Imager. GPI was built by a consortium of US and Canadian institutions to fulfill the requirements of the ExAOC Extreme Adaptive Optics Coronagraph proposal. GPI is an extreme adaptive-optics imaging polarimeter/integral-field spectrometer, which provides diffraction-limited data between 0.9 and 2.4 microns. GPI is able to directly image planets around nearby stars that are one-millionth as bright as their host star.
Gemini also supports a vigorous visitor instrument program. Instruments may be brought to either telescope for short periods of time and used for specific observing programs by the instrument teams. In return for access to Gemini, the instruments are then made available to the entire Gemini community, so that they may be used for other science projects. Instruments that have made use of this program include the Differential Speckle Survey Instrument, the Phoenix near-infrared echelle spectrometer, and the TEXES mid-infrared spectrometer. The ESPaDOnS spectrograph situated in the basement of the Canada–France–Hawaii Telescope is also being used as a "visitor instrument", even though it never moves from CFHT. The instrument is connected to Gemini-North via a 270-meter-long optic fibre. Known as GRACES, this arrangement provides very-high-resolution optical spectroscopy on an 8-meter-class telescope.
Gemini's silver coating and infrared optimization allow sensitive observations in the mid-infrared part of the spectrum. Historically, mid-infrared observations have been obtained using T-ReCS at Gemini South and Michelle at Gemini North. Both instruments have imaging and spectroscopic capabilities, though neither is currently being used at Gemini.