We present a first cut instrument design package for the proposed 25 meter Cornell-Caltech Atacama Telescope (CCAT). The primary science for CCAT can be achieved through wide field photometric imaging in the short submillimeter through millimeter (200 μm to 2 mm) telluric windows. We present strawman designs for two cameras: a 32,000 pixel short submillimeter (200 to 650 μm) camera using transition edge sensed bare bolometer arrays that Nyquist samples (@ 350 μm) a 5'×5' field of view (FoV), and a 45,000 pixel long wavelength camera (850 μm to 2 mm) that uses slot dipole antennae coupled bolometer arrays with wavelength dependent sampling that covers up to a 20' square FoV. These are our first light instruments. We also anticipate "borrowed" instruments such as direct detection and heterodyne detection spectrometers will be available at, or nearly at first light.
We describe an instrument under development at the University of Texas for observation of lunar occultations with complete spectral coverage from 1 - 13 μm and with limiting angular resolutions of 1 - 4 milliarcsecond over that range. The instrument will utilize three 2-D arrays that will enable spectral dispersion with a resolving power, R ~ 100, and permit pupil division to avoid blurring
the Fresnel fringes of an occultation. The scientific motivation for
this program is based on observations of physical properties of circumstellar disks around young, forming stars, as well as of shells around evolved stars undergoing mass loss. We also describe some examples of results with a prototype version of this instrument
that has been in use at McDonald Observatory for the last 18 months.
TEXES, the Texas Echelon Cross Echelle Spectrograph, is an ideal instrument to study molecular clouds at a spectral resolving power of 100,000 between 5 and 25 μm. In many molecular clouds, high extinction often means that no visible stars are available for off-axis guiding. At a resolving power of 100,000, only the very brightest sources can be observed while guiding on the power in the dispersed IR spectra.
We present the design of a high-speed on-axis guider for TEXES operating at 3.65 μm, a wavelength outside the spectrometer operating band where many of the target sources are still detectable for imaging. We use a new technology gold nanomesh resonant IR filter/mirror from EDTEK, that transmits 3.65 μm light to the guide detector with a peak transmittance of 60% while reflecting light from 5 μm long-ward with 98% efficiency to the dispersing elements in the spectrograph. A PC controls clocking patterns for the CRC-463 detector from Raytheon Infrared Operations and the analog to digital conversion of signals with a 14 bit A/D card. Image centroiding is done in software and then offsets are sent to the telescope for pointing adjustments or tip-tilt corrections when a tip-tilt secondary is available.
This system is a prototype designed to test the feasibility of a similar guider for EXES, the Echelon Cross Echelle Spectrograph, mounted on SOFIA, the Stratospheric Observatory for Infrared Astronomy.
Development of large, far-infrared telescopes in space has taken on a new urgency with breakthroughs in detector technology and recognition of the fundamental importance of the far-infrared spectral region to cosmological questions as well as to understanding how our own Solar System came into being. SAFIR is 10m-class far-infrared observatory that would begin development later in this decade to meet these needs. Its operating temperature (T ≤ 4 K) and instrument complement would be optimized to reach the natural sky confusion limit in the far-infrared with diffraction-limited peformance down to at least the atmospheric cutoff, λ ⪆ 40 μm. This would provide a point source sensitivity improvement of several orders of magnitude over that of SIRTF. SAFIR's science goals are driven by the fact that youngest stages of almost all phenomena in the universe are shrouded in absorption by and emission from cool dust that emits strongly in the far-infrared, 20 μm - 1mm. The main drivers on the telescope are operating temperature and aperture. SAFIR can take advantage of much of the technology under development for NGST. Because of the much less stringent requirements on optical accuracy, however, SAFIR can be developed at substantially lower cost.
This paper will summarize the stray-light study commissioned by USRA from BRO (Breault Research Organization) to estimate the level of dynamic background that might be observable at SOFIA's focal plane. This dynamic background is due to cavity and aircraft motions with respect to the inertially fixed telescope. BRO used their ASAP program to trace rays emitted from the Earth, aircraft engines, and telescope cavity to the focal plane through reflection and scatter off a number of surfaces (including Level 500 contaminated optics).