GMTNIRS: progress toward the Giant Magellan Telescope near-infrared spectrograph (original) (raw)
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Ground-based and Airborne Instrumentation for Astronomy V, 2014
GMTNIRS, the Giant Magellan Telescope near-infrared spectrograph, is a first-generation instrument for the GMT that will provide detailed spectroscopic information about young stellar objects, exoplanets, and cool and/or obscured stars. The optical and mechanical design GMTNIRS presented at a conceptual design review in October 2011 covered all accessible parts of the spectrum from 1.12 to 5.3 microns at R=50,000 (1.12-2.5 microns) and R=100,000 (3-5.3 microns). GMTNIRS uses the GMT adaptive-optics system and has a single 85 milliarcsecond slit. The instrument includes five separate spectrographs for the different atmospheric windows. By use of dichroics that divide the incident light between five separate spectrographs, it observes its entire spectral grasp in a single exposure while having only one cryogenic moving part, a rotating pupil stop. Large, highly accurate silicon immersion gratings are critical to GMTNIRS, since they both permit a design within the allowable instrument volume and enable continuous wavelength coverage on existing detectors. We describe the effort during the preliminary design phase to refine the design of the spectrograph to meet the science goals while minimizing the cost and risk involved in the grating production. We discuss different design options for the individual spectrographs at R=50,000, 67,000, 75,000, and 100,000 and their impact on science return.
GMTNIRS (Giant Magellan Telescope near-infrared spectrograph): design concept
Proceedings of …, 2010
We are designing a sensitive high resolution (R=60,000-100,000) spectrograph for the Giant Magellan Telescope (GMTNIRS, the GMT Near-Infrared Spectrograph). Using large-format IR arrays and silicon immersion gratings, this instrument will cover all of the J (longer than 1.1 μm), H, and K atmospheric windows or all of the L and M windows in a single exposure. GMTNIRS makes use of the GMT adaptive optics system for all bands. The small slits will offer the possibility of spatially resolved spectroscopy as well as superior sensitivity and wavelength coverage. The GMTNIRS team is composed of scientists and engineers at the University of Texas, the Korea Astronomy and Space Science Institute, and Kyung Hee University. In this paper, we describe the optical and mechanical design of the instrument. The principal innovative feature of the design is the use of silicon immersion gratings which are now being produced by our team with sufficient quality to permit designs with high resolving power and broad instantaneous wavelength coverage across the near-IR.
The Calibration System for IGRINS, a High Resolution Near-IR Spectrograph
2010
We present development of the calibration system for IGRINS (the Immersion GRating INfrared Spectrograph). IGRINS is a high resolution infrared spectrograph which is developed by a collaboration of the University of Texas at Austin, Korea Astronomy and Space Science Institute, and Kyung Hee University. IGRINS is the forerunner for GMTNIRS (the Giant Magellan Telescope Near Infrared Spectrograph) which has been selected for study of GMT first-light instruments. IGRINS uses a silicon immersion grating as an echelle grating and it has a resolving power of 40,000 in H(1.49μm -1.80μm) and K(1.96 μm -2.46 μm) bandpass. To establish the calibration concept of our high resolution instrument, we reviewed a few existing similar spectrographs, e.g., BOES, CRIRES, and IRCS. There are two main purposes for the calibration. Those are: 1) to get a distortion solution and a wavelength solution using line reference sources; 2) to correct pixel-to-pixel sensitivity variations by flat frames. For the ...
A concept for seeing-limited near-IR spectroscopy on the Giant Magellan Telescope
SPIE Proceedings, 2016
We present a simple seeing-limited IR spectrometer design for the Giant Magellan Telescope, with continuous R = 6000 coverage from 0.87-2.50 microns for a 0.7 slit. The instrument's design is based on an asymmetric white pupil echelle layout, with dichroics splitting the optical train into yJ, H, and K channels after the pupil transfer mirror. A separate low-dispersion mode offers single-object R ∼ 850 spectra which also cover the full NIR bandpass in each exposure. Catalog gratings and H2RG detectors are used to minimize cost, and only two cryogenic rotary mechanisms are employed, reducing mechanical complexity. The instrument dewar occupies an envelope of 1.8×1.5×1.2 meters, satisfying mass and volume requirements for GMT with comfortable margin. We estimate the system throughput at ∼ 35% including losses from the atmosphere, telescope, and instrument (i.e. all coatings, gratings, and sensors). This optical efficiency is comparable to the FIRE spectrograph on Magellan, and we have specified and designed fast cameras so the GMT instrument will have an almost identical pixel scale as FIRE. On the 6.5 meter Magellan telescopes, FIRE is read-noise limited in the y and J bands, similar to other existing near-IR spectrometers and also to JWST/NIRSPEC. GMT's twelve-fold increase in collecting area will therefore offer gains in signal-to-noise per exposure that exceed those of moderate resolution optical instruments, which are already sky-noise limited on today's telescopes. Such an instrument would allow GMT to pursue key early science programs on the Epoch of Reionization, galaxy formation, transient astronomy, and obscured star formation environments prior to commissioning of its adaptive optics system. This design study demonstrates the feasibility of developing relatively affordable spectrometers at the ELT scale, in response to the pressures of joint funding for these telescopes and their associated instrument suites.
Design and early performance of IGRINS (Immersion Grating Infrared Spectrometer)
SPIE Proceedings, 2014
The Immersion Grating Infrared Spectrometer (IGRINS) is a compact high-resolution near-infrared cross-dispersed spectrograph whose primary disperser is a silicon immersion grating. IGRINS covers the entire portion of the wavelength range between 1.45 and 2.45μm that is accessible from the ground and does so in a single exposure with a resolving power of 40,000. Individual volume phase holographic (VPH) gratings serve as cross-dispersing elements for separate spectrograph arms covering the H and K bands. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is 1ʺ x 15ʺ and the plate scale is 0.27ʺ pixel-1. The spectrograph employs two 2048 x 2048 pixel Teledyne Scientific & Imaging HAWAII-2RG detectors with SIDECAR ASIC cryogenic controllers. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be only 25mm, which permits a moderately sized (0.96m x 0.6m x 0.38m) rectangular cryostat to contain the entire spectrograph. The fabrication and assembly of the optical and mechanical components were completed in 2013. We describe the major design characteristics of the instrument including the system requirements and the technical strategy to meet them. We also present early performance test results obtained from the commissioning runs at the McDonald Observatory.
Current status of FRIDA: diffraction limited NIR instrument for the GTC
SPIE Proceedings, 2012
FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) is designed as a diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy capabilities with low (R ~ 1,500), intermediate (R ~ 4,500) and high (R ~ 30,000) spectral resolutions to operate in the wavelength range 0.9-2.5 m. The integral field unit is based on a monolithic image slicer. The imaging and IFS observing modes will use the same Teledyne 2K x 2K detector. FRIDA will be based at the Nasmyth B platform of GTC, behind the AO system. The key scientific objectives of the instrument include studies of solar system bodies, low mass objects, circumstellar outflow phenomena in advanced stages of stellar evolution, active galactic nuclei, high redshift galaxies, resolved stellar populations, semi-detached binary systems, young stellar objects and star forming environments. FRIDA is a collaborative project between the main GTC partners, namely, Spain, México and Florida. In this paper, we present the status of the instrument design as it is currently being prepared for its manufacture, after an intensive prototypes' phase and design optimization. The CDR was held in September 2011.
IFIRS: an Imaging Fourier Transform Spectrometer for NGST
1999
Due to its simultaneous deep imaging and integral field spectroscopic capability, an Imaging Fourier Transform Spectrograph (IFTS) is ideally suited to the Next Generation Space Telescope (NGST) mission, and offers opportunities for tremendous scientific return in many fields of astrophysical inquiry. We describe the operation and quantify the advantages of an IFTS for space applications. The conceptual design of the Integral Field Infrared Spectrograph (IFIRS) is a wide field (5 ′ .3 × 5 ′ .3) four-port imaging Michelson interferometer.
Instrumentation progress at the Giant Magellan Telescope project
SPIE Proceedings, 2016
Instrument development for the 24m Giant Magellan Telescope (GMT) is described: current activities, progress, status, and schedule. One instrument team has completed its preliminary design and is currently beginning its final design (G-CLEF, an optical 350-950 nm, high-resolution and precision radial velocity echelle spectrograph). A second instrument team is in its conceptual design phase (GMACS, an optical 350-950 nm, medium resolution, 6-10 arcmin field, multiobject spectrograph). A third instrument team is midway through its preliminary design phase (GMTIFS, a near-IR YJHK diffraction-limited imager/integral-field-spectrograph), focused on risk reduction prototyping and design optimization. A fourth instrument team is currently fabricating the 5 silicon immersion gratings needed to begin its preliminary design phase (GMTNIRS, a simultaneous JHKLM high-resolution, AO-fed, echelle spectrograph). And, another instrument team is focusing on technical development and prototyping (MANIFEST, a facility robotic, multifiber-feed, with a 20 arcmin field of view). In addition, a medium-field (6 arcmin, 0.06 arcsec/pix) optical imager will support telescope and AO commissioning activities, and will excel at narrow-band imaging. In the spirit of advancing synergies with other groups, the challenges of running an ELT instrument program and opportunities for cross-ELT collaborations are discussed.
NIRMOS: a wide-field near-infrared spectrograph for the Giant Magellan Telescope
Ground-based and Airborne Instrumentation for Astronomy IV, 2012
NIRMOS (Near-Infrared Multiple Object Spectrograph) is a 0.9 to 2.5 μm imager/spectrograph concept proposed for the Giant Magellan Telescope 1 (GMT). Near-infrared observations will play a central role in the ELT era, allowing us to trace the birth and evolution of galaxies through the era of peak star formation. NIRMOS' large field of view, 6.5′ by 6.5′, will be unique among imaging spectrographs developed for ELTs. NIRMOS will operate in Las Campanas' superb natural seeing and is also designed to take advantage of GMT's ground-layer adaptive optics system. We describe NIRMOS' high-performance optical and mechanical design.
MMT and Magellan Infrared Spectrograph
Publications of the Astronomical Society of the Pacific, 2012
The MMT and Magellan infrared spectrograph (MMIRS) is a cryogenic multislit spectrograph that operates from 0.9 to 2.4 microns. It will be deployed at the f/5 foci of the MMT and Magellan 6.5m telescopes. Using a fully refractive design, MMIRS offers R=1200-3000 spectral resolution with a spatial resolution of 0.2 arcsec per pixel on a 2kx2k Hawaii-2 array. We describe the optics, optics mounts, wavefront sensors, and wavelength calibration systems.