Silicon immersion gratings (SIGs) offer several advantages over the commercial echelle gratings for high
resolution infrared (IR) spectroscopy: 3.4 times the gain in dispersion or ~10 times the reduction in the
instrument volume, a multiplex gain for a large continuous wavelength coverage and low cost. We
present results from lab characterization of a large format SIG of astronomical observation quality. This
SIG, with a 54.74 degree blaze angle (R1.4), 16.1 l/mm groove density, and 50x86 mm<sup>2</sup> grating area, was
developed for high resolution IR spectroscopy (R~70,000) in the near IR (1.1-2.5 μm). Its entrance
surface was coated with a single layer of silicon nitride antireflection (AR) coating and its grating surface
was coated with a thin layer of gold to increase its throughput at 1.1-2.5 m. The lab measurements have
shown that the SIG delivered a spectral resolution of R=114,000 at 1.55 m with a lab testing
spectrograph with a 20 mm diameter pupil. The measured peak grating efficiency is 72% at 1.55 m,
which is consistent with the measurements in the optical wavelengths from the grating surface at the air
side. This SIG is being implemented in a new generation cryogenic IR spectrograph, called the Florida IR
Silicon immersion grating spectrometer (FIRST), to offer broad-band high resolution IR spectroscopy
with R=72,000 at 1.4-1.8 um under a typical seeing condition in a single exposure with a 2kx2k H2RG IR
array at the robotically controlled Tennessee State University 2-meter Automatic Spectroscopic Telescope
(AST) at Fairborn Observatory in Arizona. FIRST is designed to provide high precision Doppler
measurements (~4 m/s) for the identification and characterization of extrasolar planets, especially rocky
planets in habitable zones, orbiting low mass M dwarf stars. It will also be used for other high resolution
IR spectroscopic observations of such as young stars, brown dwarfs, magnetic fields, star formation and
interstellar mediums. An optimally designed SIG of the similar size can be used in the Silicon Immersion
Grating Spectrometer (SIGS) to fill the need for high resolution spectroscopy at mid IR to far IR (~25-300 μm) for the NASA SOFIA airborne mission in the future.
We present the results of the Astrophysics Strategic Mission Concept Study for the New Worlds Observer (NWO). We show that the
use of starshades is the most effective and affordable path to mapping and understanding our neighboring planetary systems, to opening
the search for life outside our solar system, while serving the needs of the greater astronomy community. A starshade-based mission
can be implemented immediately with a near term program of technology demonstration.
We present an overview of the near-InfraRed Multi-Object Spectrograph (IRMOS) for the Thirty Meter Telescope, as developed under a Feasibility Study at the University of Florida and Herzberg Institute of Astrophysics. IRMOS incorporates a multi-object adaptive optics correction capability over a 5-arcminute field of regard on TMT. Up to 20 independently-selectable target fields-of-view with ~2-arcsec diameter can be accessed within this field simultaneously. IRMOS provides near-diffraction-limited integral field spectroscopy over the 0.8-2.5 μm bandpass at R~1,000-20,000 for each target field. We give a brief summary of the Design Reference science cases for IRMOS. We then present an overview of the IRMOS baseline instrument design.
The Near-Infrared Camera and Fabry-Perot Spectrometer (NIC-FPS) will provide near-IR imaging over the wavelength range ~0.9-2.45 microns and medium resolution (R~10,000) full-field Fabry-Perot spectroscopy in the 1.5-2.4 micron range. Science observation will commence by mid 2004 on the Astrophysical Research Consortium 3.5-m telescope at the Apache Point Observatory in Sunspot, NM.
NIC-FPS will allow a wide variety of extragalactic, galactic, and solar system observational programs to be conducted. NIC-FPS will support two observational modes, near-IR imaging or Fabry-Perot spectroscopy. For spectroscopy of line-emitting objects, the cryogenic Fabry-Perot etalon is inserted into the optical path to generate 3D spectral datacubes at ~30 km/s spectral resolution. For narrow to broad-band imaging, the etalon is removed from the optical path. Both modes will utilize a Rockwell Hawaii 1RG 1024 x 1024 HgCdTe detector which features low dark current, low noise and broad spectral response required for astronomical observations. The optics and detector will provide a full 4.6' × 4.6' field of view at 0.27" pixel. NIC-FPS will be mounted to the ARC telescope's Nasmyth port.
NIC-FPS will significantly increase ARC's near-IR imaging and spectroscopy capabilities. We present NIC-FPS's optical design and instrument specifications.
The Galactic Exoplanet Survey Telescope (GEST) will observe a 2 square degree field in the Galactic bulge to search for extra-solar planets using a gravitational lensing technique. This gravitational lensing technique is the only method employing currently available technology that can detect Earth-mass planets at high signal-to-noise, and can measure the abundance of terrestrial planets as a function of Galactic position. GEST's sensitivity extends down to the mass of Mars, and it can detect hundreds of terrestrial planets with semi-major axes ranging from 0.7 AU to infinity. GEST will be the first truly comprehensive survey of the Galaxy for planets like those in our own Solar System.
The Hubble Space Telescope (HST) has produced dramatic images of proto-planetary disks (“proplyds”) surrounding your (<10<sup>6</sup> year old) stars embedded in the Orion Nebula. The intense UV radiation field of the high-mass Trapezium stars heats the disk surfaces, drives mass-loss, and produces bright ionization fronts. Many disks are seen in silhouette against the nebular background of the Orion Nebula, or against the proplyd’s own ionization front. The sub-arcsecond resolution and light gathering power of the Keck telescopes in the near-IR provide a unique opportunity to study the earliest phases of planetary disk evolution and disk destruction under intense UV radiation fields. We present initial results from observations of a handful of proplyds using KCAM and NIRSPEC, with and without the adaptive optics (AO) system, on Keck II. These data clearly resolve, both spatially and spectrally, ionization fronts, disks, and a microjet. The data are used to constrain mass-loss rates due to photoevaporation, disk surface wind velocity, and grain size distribution.
Visual-wavelength focal plane mosaics with 10 to 100 gigapixels may become available within the next several decades. Silicon sensor read-outs may also enable the reliable detection of individual visual wavelength photons in the near future. Such solid-state photon-counting mosaics, fed by integral-field spectrographs (IFSs) which simultaneously record the spectrum of every image element, may enable astronomers to chart the 3D structure of the entire visible Universe, and trace its physical and chemical evolution from soon after the birth of the first stars to the present. We explore the requirements of a 'cosmic atlas' sensitive to objects having 0.1 times the luminosity of the Milky Way. The proposed cosmic survey has a spatial resolution of about 0.1", a spectral resolution of R ≈ 10<sup>2</sup> to 10<sup>3</sup>, and cover the wavelength range from the near-UV to the near-IR.
We present several scenarios for the development of potential space astronomy missions and instruments over the next fifty years. It has gradually become necessary to extend our planning horizon well beyond the decade scale because of the lengthy development time for ever larger and more complex space missions, especially to enhance the efficient selection of design options for Terrestrial Planet Finder (TPF) and subsequent systems described in NASA's long-term Origins program, such as Life Finder and Planet Imager. Choices between such options should be driven by science goals and priorities, and also by the benefits of coordinating technologies developed in Origins with those needed for other U.S. and international directed-target and survey missions at all wavelengths. Even though there will be inevitable influences of scientific and technical discoveries along the way, sketching out now a variety of possible integrated technology and (to a degree) science roadmaps helps put the potential paths in context, so our early choices may more rapidly lead toward achieving likely science goals in the future.
Since 1990 the Edison program has studied designs for large, long-lived IR space telescopes incorporating intensive use of radiative cooling supplemented by mechanical refrigeration. This approach, which is now generally accepted as the most likely route to achieving large aperture and long lifetimes, led to proposals to ESA in 1993 and 1994 for a 1.7m observatory telescope operating at < 20 K as a Medium-sized mission and a Cornerstone, respectively. Extension of these ideas and the application of newer technology now indicate that a Cornerstone budget and an Ariane 5 launcher could accommodate mid- to far-IR telescopes of up to perhaps 3m aperture and/or achieve telescope temperatures of a few K--thereby attaining the full long-wavelength performance of cryogenic missions--in robust designs able to maintain their performance levels (i.e. low optics temperatures) for many years. These designs, too, have potential applications as the individual elements of spatial interferometers, for example, for searching for extrasolar terrestrial planets.
The lower stratosphere in the polar regions offers conditions for observation in the near-infrared comparable to those obtained from space. We describe a concept for a 6-meter, diluted aperture, near-infrared telescope carried by a tethered aerostat flying at 12 km altitude, to serve as a testbed for future space astronomical observatories while producing frontier science.