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Tadashi Nakajima - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity of an imaging space Infrared Interferometer
Applied optics, 2001Co-Authors: Tadashi Nakajima, Hideo MatsuharaAbstract:We study the sensitivities of space Infrared Interferometers. We formulate the signal-to-noise ratios of Infrared images obtained by aperture synthesis in the presence of source shot noise, background shot noise, and detector read noise. We consider the case in which n beams are combined pairwise at n(n - 1)/2 detectors and the case in which all the n beams are combined at a single detector. We apply the results to future missions, Terrestrial Planet Finder and Darwin. We also discuss the potential of a far-Infrared Interferometer for a deep galaxy survey.
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Sensitivity of a Ground‐based Infrared Interferometer for Aperture Synthesis Imaging
Publications of the Astronomical Society of the Pacific, 2001Co-Authors: Tadashi NakajimaAbstract:Sensitivity limits of ground-based Infrared Interferometers using aperture synthesis are presented. The motivation for this analysis is to compare Interferometers composed of multiple large telescopes and a single giant telescope with adaptive optics. In deriving these limits, perfect wave front correction by adaptive optics and perfect cophasing by fringe tracking are assumed. We consider the case in which n beams are pairwise combined at n(n)/2 detectors (nC2 Interferometer) and the case in which all the n beams are combined at a single detector (nCn Interferometer). Our analysis covers broadband observations by considering spectral dispersion of interference fringes. In the read-noise limit, the nCn Interferometer with one-dimensional baseline configuration is superior to the nC2 Interferometer, while in the background limit, the advantage of the one-dimensional nCn Interferometer is small. As a case study, we compare the point-source sensitivities of Interferometers composed of nine 10 m diameter telescopes and a 30 m diameter single telescope with adaptive optics between 1 and 10 μm for 10 σ detection in 1 hr. At J and H, the sensitivities of the Interferometers are limited to 25-24 mag by read noise and OH airglow background, while that of the single telescope is limited to 28-26 mag by OH airglow background. Longward of 2 μm, the sensitivities of the Interferometers and the single telescope are all limited by instrumental thermal background. At K, the sensitivities of the Interferometers are around 23 mag, while that of the single telescope is 27 mag. At N, the sensitivities of the Interferometers are around 10.7 mag, while that of the single telescope is 14.4 mag.
Giorgio Savini - One of the best experts on this subject based on the ideXlab platform.
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The Wide-field Imaging Interferometry Testbed (WIIT): recent progress in the simulation and synthesis of WIIT data
Optical and Infrared Interferometry and Imaging V, 2016Co-Authors: Roser Juanola-parramon, David Leisawitz, Matthew R. Bolcar, Stephen F. Maher, Stephen A. Rinehart, Alex Iacchetta, Giorgio SaviniAbstract:The Wide-field Imaging Interferometry Testbed (WIIT) is a double Fourier (DF) Interferometer operating at optical wavelengths, and provides data that are highly representative of those from a space-based far-Infrared Interferometer like SPIRIT. This testbed has been used to measure both a geometrically simple test scene and an astronomically representative test scene. Here we present the simulation of recent WIIT measurements using FIInS (the Far-Infrared Interferometer Instrument Simulator), the main goal of which is to simulate both the input and the output of a DFM system. FIInS has been modified to perform calculations at optical wavelengths and to include an extended field of view due to the presence of a detector array.
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Electromagnetic modelling of a space-borne far-Infrared Interferometer
Terahertz RF Millimeter and Submillimeter-Wave Technology and Applications IX, 2016Co-Authors: A. Donohoe, Giorgio Savini, Créidhe O'sullivan, J. Anthony Murphy, Colm Bracken, Enzo Pascale, Peter A. R. Ade, R. V. Sudiwala, Amber L. HornsbyAbstract:In this paper I will describe work done as part of an EU-funded project ‘Far-Infrared space Interferometer critical assessment’ (FISICA). The aim of the project is to investigate science objectives and technology development required for the next generation THz space Interferometer. The THz/FIR is precisely the spectral region where most of the energy from stars, exo-planetary systems and galaxy clusters deep in space is emitted. The atmosphere is almost completely opaque in the wave-band of interest so any observation that requires high quality data must be performed with a space-born instrument. A space-borne far Infrared Interferometer will be able to answer a variety of crucial astrophysical questions such as how do planets and stars form, what is the energy engine of most galaxies and how common are the molecule building blocks of life. The FISICA team have proposed a novel instrument based on a double Fourier Interferometer that is designed to resolve the light from an extended scene, spectrally and spatially. A laboratory prototype spectral-spatial Interferometer has been constructed to demonstrate the feasibility of the double-Fourier technique at far Infrared wavelengths (0.15 - 1 THz). This demonstrator is being used to investigate and validate important design features and data-processing methods for future instruments. Using electromagnetic modelling techniques several issues related to its operation at long baselines and wavelengths, such as diffraction, have been investigated. These are critical to the design of the concept instrument and the laboratory testbed.
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Astrophysical Capabilities of a Double Fourier Modulation Interferometer in Space
Fourier Transform Spectroscopy and Hyperspectral Imaging and Sounding of the Environment, 2015Co-Authors: Roser Juanola-parramon, Danielle Fenech, Giorgio SaviniAbstract:Here we present how the Far-Infrared Interferometer Instrument Simulator (FIInS) is used to simulate an observation of astronomical targets. The selection of the instrument parameters (spectral and spatial) is discussed and the obtained results analyzed.
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An end-to-end Far-Infrared Interferometer Instrument Simulator (FIInS)
Space Telescopes and Instrumentation 2014: Optical Infrared and Millimeter Wave, 2014Co-Authors: Roser Juanola-parramon, Giorgio Savini, Danielle Fenech, Catherine WalshAbstract:FIRI (Far Infra-Red Interferometer) is a concept for a spatial and spectral Space Interferometer with an operating wavelength range of 25-400 µm and sub-arcsecond angular resolution, and is based on the combination of Stellar Interferometry and Fourier Transform Spectroscopy to perform spectroscopy at high angular resolution in the Far Infrared. The resulting technique is referred to as Double Fourier Spatio-Spectral Interferometry (Mariotti and Ridgway 1988). To study the feasibility of a FIRI system the Far-Infrared Interferometer Instrument Simulator (FIInS) has been developed. To demonstrate its functionality, the simulation of an observation of a circumstellar disk around a Herbig Ae star is presented.
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FIInS. The Far-Infrared Interferometer INstrument Simulator
Imaging and Applied Optics, 2013Co-Authors: Roser Juanola-parramon, Giorgio SaviniAbstract:FIRI is a concept for a space-based spatial-spectral Interferometer with an operating wavelength range 25-300 & mu;m and subarcsecond angular resolution. The status of the design of the FIRI system via an instrument simulator is presented.
Roser Juanola-parramon - One of the best experts on this subject based on the ideXlab platform.
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The Wide-field Imaging Interferometry Testbed (WIIT): recent progress in the simulation and synthesis of WIIT data
Optical and Infrared Interferometry and Imaging V, 2016Co-Authors: Roser Juanola-parramon, David Leisawitz, Matthew R. Bolcar, Stephen F. Maher, Stephen A. Rinehart, Alex Iacchetta, Giorgio SaviniAbstract:The Wide-field Imaging Interferometry Testbed (WIIT) is a double Fourier (DF) Interferometer operating at optical wavelengths, and provides data that are highly representative of those from a space-based far-Infrared Interferometer like SPIRIT. This testbed has been used to measure both a geometrically simple test scene and an astronomically representative test scene. Here we present the simulation of recent WIIT measurements using FIInS (the Far-Infrared Interferometer Instrument Simulator), the main goal of which is to simulate both the input and the output of a DFM system. FIInS has been modified to perform calculations at optical wavelengths and to include an extended field of view due to the presence of a detector array.
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Far-Infrared Interferometer Instrument Simulator (FIInS)
A Far-Infrared Spectro-Spatial Space Interferometer, 2016Co-Authors: Roser Juanola-parramonAbstract:The Far-Infrared Interferometer Instrument Simulator, FIInS, is an instrument simulator for a Far-Infrared Spectro-Spatial Interferometer. The main goal is to simulate both the input and the output of such a system, and compare the input sky map with the synthesised one after data processing algorithms have been applied. With a modular design, intermediate outputs are also available. In this chapter the different modules created to build FIInS are described, from the sky map generator to the raw data on the detectors module.
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Astrophysical Capabilities of a Double Fourier Modulation Interferometer in Space
Fourier Transform Spectroscopy and Hyperspectral Imaging and Sounding of the Environment, 2015Co-Authors: Roser Juanola-parramon, Danielle Fenech, Giorgio SaviniAbstract:Here we present how the Far-Infrared Interferometer Instrument Simulator (FIInS) is used to simulate an observation of astronomical targets. The selection of the instrument parameters (spectral and spatial) is discussed and the obtained results analyzed.
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An end-to-end Far-Infrared Interferometer Instrument Simulator (FIInS)
Space Telescopes and Instrumentation 2014: Optical Infrared and Millimeter Wave, 2014Co-Authors: Roser Juanola-parramon, Giorgio Savini, Danielle Fenech, Catherine WalshAbstract:FIRI (Far Infra-Red Interferometer) is a concept for a spatial and spectral Space Interferometer with an operating wavelength range of 25-400 µm and sub-arcsecond angular resolution, and is based on the combination of Stellar Interferometry and Fourier Transform Spectroscopy to perform spectroscopy at high angular resolution in the Far Infrared. The resulting technique is referred to as Double Fourier Spatio-Spectral Interferometry (Mariotti and Ridgway 1988). To study the feasibility of a FIRI system the Far-Infrared Interferometer Instrument Simulator (FIInS) has been developed. To demonstrate its functionality, the simulation of an observation of a circumstellar disk around a Herbig Ae star is presented.
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FIInS. The Far-Infrared Interferometer INstrument Simulator
Imaging and Applied Optics, 2013Co-Authors: Roser Juanola-parramon, Giorgio SaviniAbstract:FIRI is a concept for a space-based spatial-spectral Interferometer with an operating wavelength range 25-300 & mu;m and subarcsecond angular resolution. The status of the design of the FIRI system via an instrument simulator is presented.
Shepard A. Clough - One of the best experts on this subject based on the ideXlab platform.
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Application of Infrared Interferometer spectrometer clear sky spectral radiance to investigations of climate variability
Journal of Geophysical Research: Atmospheres, 1996Co-Authors: Michael J. Iacono, Shepard A. CloughAbstract:An investigation of clear sky spectral radiances and their applicability as a diagnostic for climate variability is described. Global observations of outgoing longwave radiation during 1970 from the Infrared Interferometer spectrometer (IRIS) aboard Nimbus 4 cover nearly a full annual cycle, and the spectral content of the data provides unique information for examining regional and seasonal variations of spectral radiance. The IRIS radiances have been validated against a line-by-line radiative transfer model and are found to compare favorably with calculated radiances. A brightness temperature threshold technique is used to separate clear and cloudy spectra, and seasonal means of clear sky spectra are analyzed for tropical and northern midlatitude ocean areas. Brightness temperature standard deviations are also examined spectrally. Values of 1-2 K in the tropics and 2-3 K at midlatitudes in the 800-1200 cm -1 window region are consistent with observed ocean temperature variability. Spectral features in the standard deviations reflect the variation of surface temperature, tropospheric temperature, and water vapor in the tropics and the increased variability of ozone during winter in the northern hemisphere. Spectral differences between seasonal and annual mean outgoing radiance are associated with variations in atmospheric parameters, and a linear retrieval algorithm is used to quantify these changes in the tropics. Retrieved seasonal sea surface temperature (SST) differences are typically within 0.7 K of the observed SST differences. Interseasonal water column variations during this annual cycle are 5-10% over the tropical Pacific and Atlantic and 10-20% over the equatorial Indian Ocean. In general, the retrieved seasonal changes in temperature and water vapor parameters are consistent with the known conditions of the 1970 tropical ocean and atmosphere. These variations are detectable as signatures in outgoing spectral radiances and provide significant information relevant to climate change.
Sascha P. Quanz - One of the best experts on this subject based on the ideXlab platform.
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Simulating the exoplanet yield of a space-based mid-Infrared Interferometer based on Kepler statistics
Astronomy & Astrophysics, 2017Co-Authors: Jens Kammerer, Sascha P. QuanzAbstract:Aims. We predict the exoplanet yield of a space-based mid-Infrared nulling Interferometer using Monte Carlo simulations. We quantify the number and properties of detectable exoplanets and identify those target stars that have the highest or most complete detection rate. We investigate how changes in the underlying technical assumptions and uncertainties in the underlying planet population impact the scientific return. Methods. We simulated 2000 exoplanetary systems, based on planet occurrence statistics from Kepler with randomly orientated orbits and uniformly distributed albedos around each of 326 nearby ( d μ m, we quantified the number of detectable exoplanets as a function of their radii and equilibrium temperatures. Results. Approximately 315 -77 +113 exoplanets, with radii 0.5 R Earth ≤ R p ≤ 6 R Earth , were detected in at least one band and half were detected in all three bands during ~0.52 years of mission time assuming throughputs 3.5 times worse than those for the James Webb Space Telescope and ~40% overheads. Accounting for stellar leakage and (unknown) exozodiacal light, the discovery phase of the mission very likely requires 2−3 years in total. The uncertainties in planet yield are dominated by uncertainties in the underlying planet population, but the distribution of the Bond albedos also has a significant impact. Roughly 50% of the detected planets orbit M stars, which also have the highest planet yield per star; the other 50% orbit FGK stars, which show a higher completeness in the detectability. Roughly 85 planets could be habitable (0.5 R Earth ≤ R p ≤ 1.75 R Earth and 200 K ≤ T eq ≤ 450 K) and are prime targets for spectroscopic observations in a second mission phase. Comparing these results to those of a large optical/near-Infrared telescope, we find that a mid-Infrared Interferometer would detect more planets and the number of planets depends less strongly on the wavelength. Conclusions. An optimized space-based nulling Interferometer operating in the mid-Infrared would deliver an unprecedented dataset for the characterization of (small) nearby exoplanets including dozens of potentially habitable worlds.