The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a powerful new instrument being built to facility- class standards for the Gemini telescope. It takes advantage of the latest developments in adaptive optics and integral field spectrographs. GIRMOS will carry out simultaneous high-angular-resolution, spatially-resolved infrared (1 - 2.4 µm) spectroscopy of four objects within a two-arcminute field-of-regard by taking advantage of multi-object adaptive optics. This capability does not currently exist anywhere in the world and therefore offers significant scientific gains over a very broad range of topics in astronomical research. For example, current programs for high redshift galaxies are pushing the limits of what is possible with infrared spectroscopy at 8 -10- meter class facilities by requiring up to several nights of observing time per target. Therefore, the observation of multiple objects simultaneously with adaptive optics is absolutely necessary to make effective use of telescope time and obtain statistically significant samples for high redshift science. With an expected commissioning date of 2023, GIRMOS’s capabilities will also make it a key followup instrument for the James Webb Space Telescope when it is launched in 2021, as well as a true scientific and technical pathfinder for future Thirty Meter Telescope (TMT) multi-object spectroscopic instrumentation. In this paper, we will present an overview of this instrument’s capabilities and overall architecture. We also highlight how this instrument lays the ground work for a future TMT early-light instrument.
We have recently commissioned a novel infrared (0:9-1:7 μm) integral field spectrograph (IFS) called the Wide Integral Field Infrared Spectrograph (WIFIS). WIFIS is a unique instrument that offers a very large field-of-view (5000 x 2000) on the 2.3-meter Bok telescope at Kitt Peak, USA for seeing-limited observations at moderate spectral resolving power. The measured spatial sampling scale is ~ 1 x 1" and its spectral resolving power is R ~ 2; 500 and 3; 000 in the zJ (0:9 - 1:35 μm) and Hshort (1:5 - 1:7 μm) modes, respectively. WIFIS's corresponding etendue is larger than existing near-infrared (NIR) IFSes, which are mostly designed to work with adaptive optics systems and therefore have very narrow fields. For this reason, this instrument is specifically suited for studying very extended objects in the near-infrared such as supernovae remnants, galactic star forming regions, and nearby galaxies, which are not easily accessible by other NIR IFSes. This enables scientific programs that were not originally possible, such as detailed surveys of a large number of nearby galaxies or a full accounting of nucleosynthetic yields of Milky Way supernova remnants. WIFIS is also designed to be easily adaptable to be used with larger telescopes. In this paper, we report on the overall performance characteristics of the instrument, which were measured during our commissioning runs in the second half of 2017. We present measurements of spectral resolving power, image quality, instrumental background, and overall efficiency and sensitivity of WIFIS and compare them with our design expectations. Finally, we present a few example observations that demonstrate WIFIS's full capability to carry out infrared imaging spectroscopy of extended objects, which is enabled by our custom data reduction pipeline.
We present the optomechanical design and development of the Wide Integral Field Infrared Spectrograph (WIFIS). WIFIS will provide an unrivalled integral field size of 20”×50” for a near-infrared (0.9-1.7 μm) integral-field spectrograph at the 2.3-meter Steward Bok telescope. Its main optomechanical system consists of two assemblies: a room-temperature bench housing the majority of the optical components and a cryostat for a field-flattening lens, thermal blocking filter, and detector. Two additional optical subsystems will provide calibration functionality, telescope guiding, and off-axis optical imaging. WIFIS will be a highly competitive instrument for seeing-limited astronomical investigations of the dynamics and chemistry of extended objects in the near-infrared wavebands. WIFIS is expected to be commissioned during the end of 2016 with scientific operations beginning in 2017.
Polarization gratings (PGs) are a type of diffraction grating that take advantage of birefringent liquid crystal polymers to simultaneously act as a polarizing beam splitter and as a spectral dispersive element. Furthermore, PGs are capable of providing high diffraction efficiency (>90%) over a very broad wavelength range. These properties make PGs ideal for spectropolarimetry and/or high throughput, broad wavelength observations for a range of astronomical objects. Here we report on the design and on-sky testing of a prototype spectropolarimeter instrument that employs a PG optimized for operation from 500 nm to 900 nm. The prototype was mounted on a 16-inch telescope at the University of Toronto, where we carried out observations of the polarized twilight sky, a polarized standard star and two spectroscopic standard stars. Using these observations we demonstrate the PG's ability to measure linear polarization fraction and position angle, as well as recover spectra from astronomical objects.
We discuss the optical design of an infrared multi-object spectrograph (MOS) concept that is designed to take advantage of the multi-conjugate adaptive optics (MCAO) corrected field at the Gemini South telescope. This design employs a unique, cryogenic MEMS-based focal plane mask to select target objects for spectroscopy by utilizing the Micro-Shutter Array (MSA) technology originally developed for the Near Infrared Spectrometer (NIRSpec) of the James Webb Space Telescope (JWST). The optical design is based on all spherical refractive optics, which serves both imaging and spectroscopic modes across the wavelength range of 0.9−2.5 μm. The optical system consists of a reimaging system, MSA, collimator, volume phase holographic (VPH) grisms, and spectrograph camera optics. The VPH grisms, which are VPH gratings sandwiched between two prisms, provide high dispersing efficiencies, and a set of several VPH grisms provide the broad spectral coverage at high throughputs. The imaging mode is implemented by removing the MSA and the dispersing unit out of the beam. We optimize both the imaging and spectrographic modes simultaneously, while paying special attention to the performance of the pupil imaging at the cold stop. Our current design provides a 1' ♦ 1' and a 0.5' ♦ 1' field of views for imaging and spectroscopic modes, respectively, on a 2048 × 2048 pixel HAWAII-2RG detector array. The spectrograph’s slit width and spectral resolving power are 0.18'' and 3,000, respectively, and spectra of up to 100 objects can be obtained simultaneously. We present the overall results of simulated performance using optical model we designed.
The Korea Microlensing Telescope Network (KMTNet) is a network of three new 1.6-m, wide-field telescopes spread over three different sites in Chile, South Africa and Australia. Each telescope is equipped with a four square degree wide-field CCD camera, making the KMTNet an ideal facility for discovering and monitoring early supernovae and other rapidly evolving optical transients by providing 24-hour continuous sky coverage. We describe our inaugurating program of observing supernovae and optical transients using about 20% of the KMTNet time in 2015−2019. Our early results include detection of infant supernovae, novae and peculiar transients as well as numerous variable stars and low surface brightness objects such as dwarf galaxies.
We present the development of a portable SLODAR (SLOpe Detection and Ranging) instrument to measure the vertical atmosphere profile using several different telescopes (14”, 16”, and 20” aperture) and at varying worldwide sites. In particular, the portability and feasibility of this instrument motivated us to operate it at Ellesmere Island in the Canadian High Arctic. We discuss the SLODAR technique, the design of the instrument, and the results of the performance tests in the lab. The results of the Arctic site testing measurements in October and November 2012 are discussed by Maire et. al. (this conference).1
We report on the development of polarization gratings that can be used for polarimetry and/or high throughput broadband spectroscopy in astronomy. Polarization gratings are able to overcome fundamental limitations on the diffraction efficiency of conventional gratings to provide near 100% diffraction efficiency over a broad bandwidth. The broad spectral coverage of these devices will be useful for observations of gamma-ray bursts and supernovae of unknown the redshift, where spectral features may fall over a range of wavelengths. As a spectropolarimeter a polarization grating would be ideal, for example, for the study of dusts and hazes, whose polarimetric properties vary with wavelength. We present the results of a series of laboratory measurements of the diffraction efficiency and modulation efficiency of a prototype grating designed for operation from 500 to 900 nm. We find that the grating is able to achieve greater than 90% diffraction efficiency from 500 to 850 nm and modulate incident circular polarized light with an efficiency of ~ 99%. Our future plans include on-sky testing at a small local telescope, with an eventual goal of incorporating a polarization grating into the design of a microshutter array- based multi-object visible/NIR spectrograph for a 10m class facility.
We report on our development of a near-infrared multi-object spectrograph for ground-based applications using the
micro-shutter array, which was originally developed for the Near Infrared Spectrograph of the James Webb Space
Telescope. The micro-shutter array in this case acts as a source selector at a reimaged telescope focal plane. The
developed spectrograph will be implemented either with ground-layer adaptive optics system or multi-conjugate
adaptive optics system on a large telescope. This will enable for the first time fully reconfigurable infrared multi-object
spectroscopy with adaptive optics systems. We envision studying diverse astronomical objects with our spectrograph,
including high-redshift galaxies, galaxy clusters and super star clusters.
We present the current results from the development of a wide integral field infrared spectrograph (WIFIS). WIFIS offers an unprecedented combination of etendue and spectral resolving power for seeing-limited, integral field observations in the 0.9 - 1.8 μm range and is most sensitive in the 0.9 - 1.35 μ,m range. Its optical design consists of front-end re-imaging optics, an all-reflective image slicer-type, integral field unit (IFU) called FISICA, and a long-slit grating spectrograph back-end that is coupled with a HAWAII 2RG focal plane array. The full wavelength range is achieved by selecting between two different gratings. By virtue of its re-imaging optics, the spectrograph is quite versatile and can be used at multiple telescopes. The size of its field-of-view is unrivalled by other similar spectrographs, offering a 4.511x 1211 integral field at a 10-meter class telescope (or
2011 x 5011 at a 2.3-meter telescope). The use of WIFIS will be crucial in astronomical problems which require
wide-field, two-dimensional spectroscopy such as the study of merging galaxies at moderate redshift and nearby star/planet-forming regions and supernova remnants. We discuss the final optical design of WIFIS, and its predicted on-sky performance on two reference telescope platforms: the 2.3-m Steward Bok telescope and the
10.4-m Gran Telescopio Canarias. We also present the results from our laboratory characterization of FISICA.
IFU properties such as magnification, field-mapping, and slit width along the entire slit length were measured by our tests. The construction and testing of WIFIS is expected to be completed by early 2013. We plan to commission the instrument at the 2.3-m Steward Bok telescope at Kitt Peak, USA in Spring 2013.
We present the science cases with the Korea Microlensing Telescope Network (KMTNet) which consists of three widefield
1.6 m telescopes distributed in Chile, South Africa, and Australia, respectively, providing unique continuous sky
coverage with the three telescopes. The primary scientific goal of the KMTNet project is to explore the structure and
diversity of planetary systems and variable objects. Since the system is mainly optimized to conduct gravitational
microlensing surveys, it will enable detections of very low-mass exoplanets, potentially down to the mass of Mars that
are inaccessible by other ground-based techniques. In addition to the primary science, it is possible to conduct a variety
of other observational programs with the KMTNet system, including photometric studies of nearby galaxies and galaxy
clusters, discovery of supernovae and their follow-up observations, and observations of near-Earth objects. We expect
synergies between the KMTNet project with other similar or complementary projects in the southern sky, such as
SkyMapper.
We present the optical design of the Wide Integral Field Infrared Spectrograph (WIFIS) which provides an unprecedented
combination of the integral field size and the spectral resolving power in the near-infrared wavebands.
The integral field size and spectral resolving power of WIFIS are ~ 5× 12on a 10-m telescope (or equivalently
13× 30on a 4-m telescope) and ~ 5300, respectively. Therefore, the affordable etendue of WIFIS is larger
than any other near-infrared integral field spectrographs while its spectral resolving power is comparable to the
highest value provided by other spectrographs. WIFIS optical system comprises an Offner relay-based pre-slit
unit, an image slicer for integral-field unit, a collimator, diffraction gratings, and a spectrograph camera. For the
integral field unit, WIFIS uses the Florida Image Slicer for Infrared Cosmological and Astrophysics which is a set
of 3 monolithic mirror arrays housing 22 image slicers. The collimator system consists of one off-axis parabola
and two lenses, while WIFIS relies on 3 different gratings to cover the entire JHK bands. The spectrograph
camera uses 6 lenses of CaF2 and SFTM16, delivering the f/3 final beam onto a Hawaii II RG 2K × 2K detector
array. WIFIS will be an ideal instrument to study the dynamics and chemistry of extended objects.
We present the results of the design studies of the science calibration system for the adaptive optics and infrared
instruments of the Thirty Meter Telescope. The two major requirements of the science calibration system are to provide
pupil-simulated telescope beams to the adaptive optics system for calibration of the telescope pupil and to provide flatfielding
and wavelength-calibration illuminations to client instruments of the adaptive optics system. Our current system
is composed an integrating sphere with calibration light sources, a retractable pupil-mask system, a lens assembly
consisting of a pair of achromatic triplets, and fold mirrors. This system appears to be capable of producing highlyuniform
of f/15 beams at the telescope focal plane and pupil simulation at a pupil location within the adaptive optics
system. We describe the present design and development of the calibration system along with relevant analyses.
We report the performance of Triplespec from commissioning observations on the 200-inch Hale Telescope
at Palomar Observatory. Triplespec is one of a set of three near-infrared, cross-dispersed spectrographs
covering wavelengths from 1 - 2.4 microns simultaneously at a resolution of ~2700. At Palomar, Triplespec
uses a 1×30 arcsecond slit. Triplespec will be used for a variety of scientific observations, including
moderate to high redshift galaxies, star formation, and low mass stars and brown dwarfs. When used in
conjunction with an externally dispersed interferometer, Triplespec will also detect and characterize
extrasolar planets.
We present the design, construction, and test observations of a new infrared (IR) photon-counting photometer
for astronomy based on the edge-illuminated solid-state photomultiplier (EISSPM). The EISSPM has a photon-counting
capability over the 0.4-28 μm range with a nanosecond-scale intrinsic detector time resolution. Its
quantum efficiency (QE) peaks greater than or equal to 30 % in the near-IR, which is much higher than the previous SSPM with back
illumination. After characterizing the dark noise of the EISSPM at its operational temperature range, we develop
an EISSPM-based IR photon-counting photometer for astronomical observations. This includes the design and
construction of a full optical, cryo-mechanical, and electronics system as well as the software for operating the
instrument on telescopes. We report the results of our test observations of the Crab Nebula pulsar using this
new instrument on the Palomar Hale 5-m telescope with 10-μs time resolution.
Four institutions are collaborating to design and build three near identical R ~2700 cross-dispersed near-infrared spectrographs for use on various 5-10 meter telescopes. The instrument design addresses the common observatory need for efficient, reliable near-infrared spectrographs through such features as broad wavelength coverage across 6 simultaneous orders (0.8 - 2.4 microns) in echelle format, real-time slit viewing through separate optics and detector, and minimal moving parts. Lastly, the collaborators are saving money and increasing the likelihood of success through economies of scale and sharing intellectual capital.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.