A mid-infrared (MIR) imager and spectrometer is being investigated for possible construction in the early operation of the Thirty Meter Telescope (TMT). Combined with the MIR adaptive optics (AO) system (MIRAO), the instrument will afford ~15 times higher sensitivity and ~4 times better spatial resolution (0.07”) at 10μm compared to 8m-class telescopes. Additionally, through exploiting the large collection area of the TMT, the high-dispersion spectroscopy mode will be unrivaled by other ground- and space-based facilities. These combined capabilities offer the possibility for breakthrough science, as well as ‘workhorse’ observing modes of imaging and low/moderate spectral resolution. In this paper we summarize the primary science drivers that are guiding the instrument design.
To help the prospective observer take full advantage of the mid-IR capability of Gemini South, we characterize a key aspect of the mid-IR performance of the 8-meter telescope at Gemini-S, namely, the appearance and stability of its delivered mid-IR image profiles, with the goal of demonstrating that it can be used with a level
of precision not used before. About 2000 images obtained with T-ReCS (a facility mid-IR camera at Gemini-S) between late 2003 and early 2009 were used for our image quality analysis. All targets are flux standards and recorded at one or more of the four bands Si-2 (8.74 μm), N (10.36 μm), Si-5 (11.66 μm), and Qa (18.3 μm).
A non-linear least squares fitting of three profile models (Lorentzian, Gaussian, and Moffat) was performed on
each image, and key parameters such as FWHM, ellipticity, position angle and Strehl-ratio were measured from
the fitted profile. We find that the long-time-scale image quality is quite stable in terms of profile width or
ellipticity, though short-time-scale variation is evident. We also examined the correlation between image quality
and many ambient parameters and confirmed the interdependence between the image quality in the Qa band
and the ambient humidity. The ellipticity of the profile was analyzed statistically as well. The average profiles
for different filters can be used as important references in the future when a high-quality profile reference is not
available during an observation.
A mid-infrared (MIR) imager and spectrometer is being investigated for possible consideration for construction
in the early operation of the Thirty Meter Telescope (TMT). Combined with adaptive optics for the MIR, the
instrument will afford 15 times higher sensitivity (0.1mJy as 5 sigma detection in 1hour integration in the N-band
imaging) and 4 times better spatial resolution (0.08") at 10μm compared to 8m-class telescopes. In addition, its
large light-gathering power allows high-dispersion spectroscopy in the MIR that will be unrivaled by any other
facility. We, a collaborating team of Japanese and US MIR astronomers, have carefully considered the science
drivers for the TMT MIR instrument. Such an instrument would offer both broad and potentially transformative
science. Furthering the science cases for the MIRES1, where high-dispersion spectroscopy was emphasized, we
discuss additional capabilities for the instrument drawn from the enlarged science cases. The science cases include
broader areas of astronomical fields: star and planet formation, solar system bodies, evolved stars, interstellar
medium (ISM), extragalaxies, and cosmology. Based on these science drivers, essential instrument capabilities
and key enhancement are discussed (see the companion paper Tokunaga et al. 20102): specifically imaging, lowand
high-spectral resolution modes, integral field spectroscopy, and polarimetry.
A mid-infrared imager and spectrometer is under consideration for construction in the first decade of the Thirty-
Meter Telescope (TMT) operation (see the companion paper by Okamoto). MIRES, a mid-infrared high-spectral
resolution optimized instrument, was previously proposed to provide these capabilities to the TMT community.
We have revised the design in order to provide an improved optical design for the high-spectral resolution
mode with R=120,000, improved imaging with sky chopping, low-spectral resolution mode with an integral
field spectrograph, and polarimetry. In this paper we describe the optical design concepts currently under
CanariCam is the facility multi-mode mid-IR camera developed by the University of Florida for the 10-meter Gran
Telescopio Canarias (GTC) on La Palma. CanariCam has four science modes that provide the GTC community with an
especially powerful research tool for imaging, grating spectroscopy, coronagraphy, and dual-beam polarimetry.
Instrument commissioning in the laboratory at the University of Florida indicates that all modes perform as required, and
the next step is on-telescope commissioning. After commenting on the instrument status, we will review key features of
each of these science modes, with emphasis on illustrating each mode with science examples that put the system
performance, particularly the anticipated sensitivity, into perspective.
Mid-infrared polarimetry remains an underexploited technique; where available it is limited in spectral coverage from
the ground, and conspicuously absent from the Spitzer, JWST and Herschel instrument suites. The unique characteristics
of SOFIA afford unprecedented spectral coverage and sensitivity in the mid-infrared waveband. We discuss the
preliminary optical design for a 5-40μm spectro-polarimeter for use on SOFIA, the SOFIA Mid-InfraRed Polarimeter
(SMIRPh). The design furthers the existing 5-40μm imaging and spectroscopic capabilities of SOFIA, and draws on
experience gained through the University of Florida's mid-IR imagers, spectrometer and polarimeter designs of T-ReCS
and CanariCam. We pay special attention to the challenges of obtaining polarimetric materials suitable at both these
wavelengths and cryogenic temperatures. Finally, we (briefly) present an overview of science highlights that could be
performed from a 5-40μm imaging- and spectro-polarimeter on SOFIA. Combined with the synergy between the
possible future far-IR polarimeter, Hale, this instrument would provide the SOFIA community with unique and exciting
science capabilities, leaving a unique scientific legacy.
CanariCam is the facility multi-mode mid-IR camera developed by the University of Florida (UF) for the 10.4-
meter Gran Telescopio Canarias (GTC). CanariCam contains a 320 × 240-pixel Raytheon array, which will
Nyquist-sample the diffraction-limited point-spread-function at wavelengths longer than 8 microns, yielding a
field of view of 26"×19". In Aug. 2007, the University of Florida instrument team held a successful Acceptance
Testing (AT) of CanariCam. We describe key performance requirements, and compare these to the actual performance
during formal AT. Among the results considered are detector noise characteristics, image quality, and
throughput. We focus particularly on the unique dual-beam polarimetric modes. We have demonstrated that
with a half-wave plate, it achieves or exceeds the design goals for imaging both polarization planes simultaneously.
CanariCam is the facility mid-infrared (MIR) instrument for the Gran Telescopio Canarias (GTC), a 10.4m
telescope at the Observatorio del Roque de los Muchachos on La Palma. One of the science drivers for CanariCam is the study of active galactic nuclei (AGN). We will exploit the instrument's high sensitivity in imaging,
spectroscopy, and polarimetry modes to answer fundamental questions of AGN and their host galaxies. Dust in
the nucleus of an active galaxy reprocesses the intrinsic radiation of the central engine to emerge in the MIR.
Current work demonstrates that the hot dust immediately associated with the AGN, which blocks direct views of
the AGN from some lines of sight, is confined to small (parsec) scales. Thus, high spatial resolution is essential to
probe the "torus" of unified AGN models separate from the host galaxy. CanariCam provides a 0.08" pixel scale
for Nyquist sampling the diffraction-limited point spread function at 8μm, and narrow (0.2") spectroscopy slits
(with R=120-1300). New observations with the GTC/CanariCam will provide key constraints on the physical
conditions in the clumpy torus, and we will sensitively determine AGN obscuration as a function of nuclear
activity. We will therefore address the fueling process and its relationship to the torus, the interaction with the
host galaxy, and dust chemistry. These data will be essential preparation for the next generation of telescopes
that will observe the distant universe directly to explore galaxy and black hole formation and evolution, and the
GTC/CanariCam system uniquely provides multiple modes to probe AGN.
Mid-infrared polarimetry remains an underexploited technique; where available it is limited in spectral coverage from
the ground, and conspicuously absent from both the Spitzer and JWST instrument suites. The unique characteristics of
SOFIA affords unprecedented spectral coverage and sensitivity in the mid-infrared waveband, offering new vistas in the
exploration of astrophysical objects, including (a) galaxies and AGN, (b) star formation regions and (c) debris disks.
Furthering the existing 5-40μm imaging and spectroscopic capabilities of SOFIA, and the University of Florida's mid-IR
imagers, spectrometer and polarimeter designs of T-ReCS and CanariCam, we present an overview of science highlights
that could be performed from a ~5-40μm imaging- and spectro-polarimeter on SOFIA. A secondary science driver is the
inclusion of low- to moderate- resolution (total flux) spectroscopy at these wavelengths. Such an instrument concept
would plug an unfilled area of both SOFIA and space-based instrumentation, providing SOFIA with unique and exciting
The University of Florida is developing a mid-infrared camera for the 10.4-meter Gran Telescopio CANARIAS. CanariCam has four science modes and two engineering modes, which use the same 320 x 240-pixel, arsenic-doped silicon, blocked-impurity-band detector from Raytheon. Each mode can be remotely selected quickly during an observing sequence. The pixel scale is 0.08 arcsec, resulting in Nyquist sampling of the diffraction-limited point-spread-function at 8 μm, the shortest wavelength for which CanariCam is optimized. The total available field of view for imaging is 26 arcsec x 19 arcsec. The primary science mode will be diffraction-limited imaging using one of several available spectral filters in the 10 μm (8-14 μm) and 20 μm (16-25 μm) atmospheric windows. Any one of four plane gratings can be inserted for low and moderate-resolution (R = 100 - 1300) slit spectroscopy in the 10 and 20-μm regions. Insertion of appropriate field and pupil stops converts the camera into a coronagraph, while insertion of an internal rotating half-wave plate, a field mask, and a Wollaston prism converts the camera into a dual-beam polarimeter.
For background-limited observations such as those at mid-infrared wavelengths, an increase in telescope aperture not only improves the angular resolution (as it does at all wavelengths) but also leads to very large increases in sensitivity because of the reduced background within the diffraction-limited point spread function. In this presentation we look at the magnitude of that increase for several different operational modes of mid-infrared instrumentation, and we consider some of the implications for science on the current generation of 8-10 meter telescopes.
NASA's Stratospheric Observatory for IR Astronomy (SOFIA) will enable unprecedented IR acuity at wavelengths obscured from the ground. To help open this new chapter in the exploration of the IR universe, we are developing the Airborne IR Echelle Spectrometer (AIRES) as a facility science instrument. Full funding was awarded for a four year development in October, 1997. The instrument is scheduled to come on-line with the observatory in the Fall of 2001. It will be used to investigate a broad range of phenomena that occur in the interstellar medium. AIRES will use a 1200 mm long, 76 degree blaze angle echelle to combine high resolution spectroscopy with diffraction-limited imaging in the cross-dispersion direction. Its three 2D detector arrays will prove good sensitivity over a decade in wavelength. An additional array will be used as a slit viewer for (lambda) <EQ 28 micrometers to image source morphology and to verify telescope pointing. Our scientific motivation, preliminary optical design and packaging, focal plane configuration, echelle prototyping, and cryostat layout are described.
The University of Florida is developing the mid-IR imager, called GatirCam, to be used primarily, but not solely, at the southern hemisphere Gemini telescope at Cerro Pachon, Chile. Key features of GatirCam are its fully reflective optics, its very high mechanical rigidity, and the fact that the associated electronics are very similar to those is in use successfully on similar instrumentation. Design studies for GatirCam indicate that it will meet or exceed all critical requirements of image quality and performance. A low-resolution spectroscopic mode is also currently under consideration for implementation in GatirCam.
The Marshall Space Flight Center, Alabama, in a teaming arrangement with the University of Florida, Gainesville, and the Joint Astronomy Center, Hawaii, has completed a comprehensive investigation into the feasibility of a low-cost infrared space astronomy mission. This mission would map the emission of molecular hydrogen in our galaxy at two or three previously inaccessible mid-IR wavelengths, and provide information on the temperatures. The feasibility of the low-cost mission hinged on whether a thermal design could be found which would allow sufficient passive cooling of the telescope to elimiate the need for a large, expensive dewar. An approach has been found which can provide telescope temperatures on the order of 50 K, which makes the mission feasible at low cost in low-Earth orbit.