The Giant Magellan Telescope project is proceeding with design, fabrication, and site construction. The first of the seven required 8.4-m primary mirror segments is completed and in storage, three segments are in various stages of grinding and polishing, and the fifth segment has been cast. Industry contracts are underway to complete the design of the telescope structure. Residence buildings and other facilities needed to support construction at the Las Campanas site in Chile are complete. Hard rock excavation is imminent in preparation for the pouring of concrete for the telescope pier and other foundations. Computational fluid dynamics analysis is informing the design of the telescope enclosure, and further construction work packages are being readied for tender. Seismic design considerations have resulted in the incorporation of a seismic isolation system into the telescope pier, as well as modifications to the primary mirror support system. Designs for the fast-steering and adaptive secondary mirrors, science instruments, and other subsystems are maturing. Prototyping is underway in various aspects, including on-sky testing of wavefront sensing and control elements, and the telescope metrology system. Our fabrication and construction schedule calls for engineering first light with a subset of primary mirror segments in late 2023, with buildout to the full configuration occurring in stages, paced by the availability of primary mirror segments and other components.
The Giant Magellan Telescope Project is in the construction phase. Production of the primary mirror segments is underway with four of the seven required 8.4m mirrors at various stages of completion and materials purchased for segments five and six. Development of the infrastructure at the GMT site at Las Campanas is nearing completion. Power, water, and data connections sufficient to support the construction of the telescope and enclosure are in place and roads to the summit have been widened and graded to support transportation of large and heavy loads. Construction pads for the support buildings have been graded and the construction residence is being installed. A small number of issues need to be resolved before the final design of the telescope structure and enclosure can proceed and the GMT team is collecting the required inputs to the decision making process. Prototyping activities targeted at the active and adaptive optics systems are allowing us to finalize designs before large scale production of components begins. Our technically driven schedule calls for the telescope to be assembled on site in 2022 and to be ready to receive a subset of the primary and secondary mirror optics late in the year. The end date for the project is coupled to the delivery of the final primary mirror segments and the adaptive secondary mirrors that support adaptive optics operations.
The Giant Magellan Telescope (GMT) is a 25.4-m diameter, optical/infrared telescope that is being built by an international consortium of universities and research institutions as one of the next generation of Extremely Large Telescopes. The primary mirror of GMT consists of seven 8.4 m borosilicate honeycomb mirror segments that are optically conjugate to seven corresponding segments in the Gregorian secondary mirror. Fabrication is complete for one primary mirror segment and is underway for the next two. The final focal ratio of the telescope is f/8.2, so that the focal plane has an image scale of 1.02 arcsec/mm. GMT will be commissioned using a fast-steering secondary mirror assembly comprised of conventional, rigid segments to provide seeing-limited observations. A secondary mirror with fully adaptive segments will be used in standard operation to additionally enable ground-layer and diffraction-limited adaptive optics. In the seeing limited mode, GMT will provide a 10 arcmin field of view without field correction. A 20 arcmin field of view will be obtained using a wide-field corrector and atmospheric dispersion compensator. The project has recently completed a series of sub-system and system-level preliminary design reviews and is currently preparing to move into the construction phase. This paper summarizes the technical development of the GMT sub-systems and the current status of the GMT project.
The Giant Magellan Telescope (GMT) is a 25.4-m optical/infrared telescope constructed from seven 8.4-m primary
mirror segments. The collecting area is equivalent to a 21.6-m filled aperture. The instrument development program was
formalized about two years ago with the initiation of 14-month conceptual design studies for six candidate instruments.
These studies were completed at the end of 2011 with a design review for each. In addition, a feasibility study was
performed for a fiber-feed facility that will direct the light from targets distributed across GMT's full 20 arcmin field of
view simultaneously to three spectrographs. We briefly describe the features and science goals for these instruments, and
the process used to select those instruments that will be funded for fabrication first. Detailed reports for most of these
instruments are presented separately at this meeting.
The Giant Magellan Telescope (GMT) is a 25-meter optical/infrared extremely large telescope that is being built by an
international consortium of universities and research institutions. It will be located at the Las Campanas Observatory,
Chile. The GMT primary mirror consists of seven 8.4-m borosilicate honeycomb mirror segments made at the Steward
Observatory Mirror Lab (SOML). Six identical off-axis segments and one on-axis segment are arranged on a single
nearly-paraboloidal parent surface having an overall focal ratio of f/0.7. The fabrication, testing and verification
procedures required to produce the closely-matched off-axis mirror segments were developed during the production of
the first mirror. Production of the second and third off-axis segments is underway.
GMT incorporates a seven-segment Gregorian adaptive secondary to implement three modes of adaptive-optics
operation: natural-guide star AO, laser-tomography AO, and ground-layer AO. A wide-field corrector/ADC is available
for use in seeing-limited mode over a 20-arcmin diameter field of view. Up to seven instruments can be mounted
simultaneously on the telescope in a large Gregorian Instrument Rotator. Conceptual design studies were completed for
six AO and seeing-limited instruments, plus a multi-object fiber feed, and a roadmap for phased deployment of the GMT
instrument suite is being developed.
The partner institutions have made firm commitments for approximately 45% of the funds required to build the
telescope. Project Office efforts are currently focused on advancing the telescope and enclosure design in preparation for
subsystem- and system-level preliminary design reviews which are scheduled to be completed in the first half of 2013.
Cerro Las Campanas located at Las Campanas Observatory in Chile has been selected as the site for the Giant Magellan
Telescope. We report results obtained since the commencement, in 2005, of a systematic site testing survey of potential
GMT sites at LCO. Seeing data have been obtained at three potential sites, and are compared with identical data taken at
the site of the twin Magellan 6.5m telescopes. In addition, measurements of the turbulence profile of the free-atmosphere
have been collected. Co. Las Camapanas and the Magellan site are nearly identical in their seeing statistics, and
apparently their average ground-layer characteristics.
Cerro Las Campanas located at Las Campanas Observatory (LCO) in Chile has been selected as the site for the Giant
Magellan Telescope. We report results obtained since the commencement, in 2005, of a systematic site testing survey of
potential GMT sites at LCO. Atmospheric precipitable water vapor (PWV) adversely impacts mid-IR astronomy
through reduced transparency and increased background. Prior to the GMT site testing effort, little was known regarding
the PWV characteristics at LCO and therefore, a multi-pronged approach was used to ensure the determination of the
fraction of the time suitable for mid-IR observations. High time resolution monitoring was achieved with an Infrared
Radiometer for Millimeter Astronomy (IRMA) from the University of Lethbridge deployed at LCO since September of
2007. Absolute calibrations via the robust Brault method (described in Thomas-Osip et al.1) are provided by the
Magellan Inamori Kyocera Echelle (MIKE), mounted on the Clay 6.5-m telescope on a timescale of several per month.
We find that conditions suitable for mid-IR astronomy (PWV < 1.5 mm) are concentrated in the southern winter and
spring months. Nearly 40% of clear time during these seasons have PWV < 1.5mm. Approximately 10% of these nights
meet our PWV requirement for the entire night.
Cerro Las Campanas located at Las Campanas Observatory (LCO) in Chile has been selected as the site for the Giant
Magellan Telescope. We report results obtained since the commencement, in 2005, of a systematic site testing survey of
potential GMT sites at LCO. Meteorological (cloud cover, temperature, pressure, wind, and humidity) and DIMM
seeing data have been obtained at three potential sites, and are compared with identical data taken at the site of the twin
Magellan 6.5m telescopes. In addition, measurements of the turbulence profile of the free-atmosphere above LCO have
been collected with a MASS/DIMM. Furthermore, we consider photometric quality, light pollution, and precipitable
water vapor (PWV). LCO, and Co. Las Campanas in particular, have dark skies, little or no risk of future light pollution,
excellent seeing, moderate winds, PWV adequate for mid-IR astronomy during a reasonable fraction of the nights, and a
high fraction of clear nights overall. Finally, Co. Las Campanas meets or exceeds all the defined science requirements.
The Giant Magellan Telescope (GMT) is a 24.5m diameter optical/infrared telescope. Its seven 8.4m primary mirrors
give it a collecting area equivalent to a 21.4m filled aperture. The ten GMT partners are constructing the telescope at the
Las Campanas Observatory in Chile with first light planned for the end of 2018. In this paper, we describe the plans for
the first-generation focal plane instrumentation for the telescope. The GMTO Corporation has solicited studies for
instruments capable of carrying out the broad range of objectives outlined in the GMT Science Case. Six instruments
have been selected for 14 month long conceptual design studies. We briefly describe the features of these instruments
and give examples of the major science questions that they can address.
KEYWORDS: Adaptive optics, Galactic astronomy, Stars, Spectrographs, Large telescopes, Signal to noise ratio, Telescopes, Point spread functions, Sensors, Turbulence
Ground-layer Adaptive Optics offers a unique approach to enhancing the power of large telescopes to explore a wide
range of astrophysical phenomena. By accessing wide fields of view with image concentrations that are significantly
improved over natural seeing, ground-layer AO systems can probe stellar populations in crowded and confused regions
of the Milky Way and nearby galaxies, probe the internal dynamics of large samples of galaxies in the distant universe
and provide a cost effective path towards highly multiplexed observations of large samples. The improved image
concentration over large fields of view offered by ground-layer AO will allow significant gains in sensitivity for multiobject
spectrographs operating in the near-IR. This will lead to improved understanding of the formation of the first
galaxies and stars as well as the evolution of massive galaxies when the Universe was a few billion years old. Groundlayer
AO systems have the potential to eliminate poor seeing from most astronomical sites and to improve the
productivity of large and extremely large telescopes.
The FourStar infrared camera is a 1.0-2.5 μm (JHKs) near infrared camera for the Magellan Baade
6.5m telescope at Las Campanas Observatory (Chile). It is being built by Carnegie Observatories and
the Instrument Development Group and is scheduled for completion in 2009. The instrument uses four
Teledyne HAWAII-2RG arrays that produce a 10.9' × 10.9' field of view. The outstanding seeing at the
Las Campanas site coupled with FourStar's high sensitivity and large field of view will enable many
new survey and targeted science programs.
The Giant Magellan Telescope (GMT) is a joint project of a consortium of universities and research institutions to build and operate a 21.5-m equivalent aperture astronomical telescope for use at visible and IR wavelengths. This paper briefly summarizes the science goals for the project and provides an overview of the preliminary telescope and enclosure concepts and site test program. The telescope is a Gregorian design with a fast, f/0.7, primary mirror that allows a compact and stiff mount structure. The 25.3-meter diameter primary mirror consists of six off-axis 8.4-meter circular mirrors arranged in a hexagon around a center 8.4-meter mirror. The Gregorian secondary mirror is adaptive allowing two-mirror, wide-field adaptive optics. Several corrector designs have been studied for wide-field applications and one such design is shown. Instruments being considered for GMT provide a wide range of scientific capabilities. Instruments mount below the primary mirror on an instrument platform. Instrument mounting and servicing provisions are summarized.
In June 1997, NASA made the decision to extend the end of the Hubble Space Telescope (HST) mission from 2005 until 2010. As a result, the age of the instruments on board the HST became a consideration. After careful study, NASA decided to ensure the imaging capabilities of the HST by replacing the Wide Field Planetary Camera 2 with a low-cost facility instrument, the Wide Field Camera 3. This paper provides an overview of the scientific goals and capabilities of the instrument.
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