CanariCam Mid-infrared Drift Scanning: Improved Sensitivity and Spatial Resolution

Abstract Ground-based mid-infrared (MIR) astronomical observations require the removal of the fast time variable components of (a) sky/background variation and (b) array background. Typically, this has been achieved through oscillating the telescope’s secondary mirror a few times a second, a process termed “chopping.” However, chopping reduces on-object photon collection time, imposes stringent demands on the secondary mirror, requires nodding of the telescope to remove the radiative offset imprinted by the chopping, and relies on an often-fixed chop-frequency regardless of the sky conditions in the actual observations. In the 30 m telescope era, secondary mirror chopping is impracticable. However, if the sky and background are sufficiently stable, drift scanning holds the promise to remove the necessity of chopping. In this paper, we report our encouraging drift scanning results using the CanariCam MIR instrument on the 10.4 m Gran Telescopio Canarias and the implications to future instruments and experiments.

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A Blended Sea Ice Concentration Product from AMSR2 and VIIRS

Remote Sensing ◽

10.3390/rs13152982 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2982

Author(s):

Richard Dworak ◽

Yinghui Liu ◽

Jeffrey Key ◽

Walter N. Meier

Keyword(s):

Sea Ice ◽

Spatial Resolution ◽

Infrared Imaging ◽

High Spatial Resolution ◽

Sea Ice Concentration ◽

Clear Sky ◽

Ice Concentration ◽

Best Linear Unbiased ◽

The Individual ◽

Sky Conditions

An effective blended Sea-Ice Concentration (SIC) product has been developed that utilizes ice concentrations from passive microwave and visible/infrared satellite instruments, specifically the Advanced Microwave Scanning Radiometer-2 (AMSR2) and the Visible Infrared Imaging Radiometer Suite (VIIRS). The blending takes advantage of the all-sky capability of the AMSR2 sensor and the high spatial resolution of VIIRS, though it utilizes only the clear sky characteristics of VIIRS. After both VIIRS and AMSR2 images are remapped to a 1 km EASE-Grid version 2, a Best Linear Unbiased Estimator (BLUE) method is used to combine the AMSR2 and VIIRS SIC for a blended product at 1 km resolution under clear-sky conditions. Under cloudy-sky conditions the AMSR2 SIC with bias correction is used. For validation, high spatial resolution Landsat data are collocated with VIIRS and AMSR2 from 1 February 2017 to 31 October 2019. Bias, standard deviation, and root mean squared errors are calculated for the SICs of VIIRS, AMSR2, and the blended field. The blended SIC outperforms the individual VIIRS and AMSR2 SICs. The higher spatial resolution VIIRS data provide beneficial information to improve upon AMSR2 SIC under clear-sky conditions, especially during the summer melt season, as the AMSR2 SIC has a consistent negative bias near and above the melting point.

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Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use

Review of Scientific Instruments ◽

10.1063/1.4954405 ◽

2016 ◽

Vol 87 (6) ◽

pp. 063119 ◽

Cited By ~ 22

Author(s):

Mbaye Faye ◽

Michel Bordessoule ◽

Brahim Kanouté ◽

Jean-Blaise Brubach ◽

Pascale Roy ◽

...

Keyword(s):

Synchrotron Radiation ◽

Spatial Resolution ◽

Infrared Detector ◽

Mid Infrared ◽

Radiation Use

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A New Model for Long-Term Stochastic Analysis and Prediction—Part I: Theoretical Background

Journal of Ship Research ◽

10.5957/jsr.1992.36.1.1 ◽

1992 ◽

Vol 36 (01) ◽

pp. 1-16

Author(s):

G. A. Athanassoulis ◽

P. B. Vranas ◽

T. H. Soukissian

Keyword(s):

Time Scale ◽

Random Function ◽

Spectral Characteristics ◽

Time History ◽

Time Variable ◽

Sea Surface ◽

Surface Elevation ◽

Fast Time ◽

Slow Time

A new approach for calculating the long-term statistics of sea waves is proposed. A rational long-term stochastic model is introduced which recognizes that the wave climate at a given site in the ocean consists of a random succession of individual sea states, each sea state possessing its own duration and intensity. This model treats the sea-surface elevation as a random function of a "fast" time variable, and the time history of the spectral characteristics of the successive sea states as a random function of a "slow" time variable. By developing an appropriate conceptual framework, it becomes possible to express various probabilistic characteristics of the sea-surface elevation, which are sensible only in the fast-time scale, in terms of the statistics of sea-states duration and intensity, which is meaningful only in the slow-time scale. As an example, we study the random quantity MU(T) = "number of maxima of the sea-surface elevation lying above the level u and occurring during a long-term time period [0,T]." Exploiting the proposed framework, it is shown that, under certain clearly defined assumptions, Mu(T) can be given the structure of a renewal-reward (cumulative) process, whose interarrival times correspond to the duration of successive sea states. Thus, using renewal theory, the complete characterization of the probability structure of MU(T) is obtained. As a consequence, the long-term probability distribution function of the individual wave height is rigorously defined and calculated. The relation of the present results with corresponding ones previously obtained is thoroughly discussed. The proposed model can be extended twofold: either by replacing some of the simplifying assumptions by more realistic ones, or by extending the model for treating the corresponding problems for ship and structures responses.

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Conductivity Mapping in Graphene through Scattering-Type Scanning Near-Field Optical Microscopy in the Mid-Infrared and Terahertz Spectral Region with 25nm Spatial Resolution

ECS Meeting Abstracts ◽

10.1149/ma2018-01/10/872 ◽

2018 ◽

Keyword(s):

Optical Microscopy ◽

Spatial Resolution ◽

Spectral Region ◽

Near Field ◽

Mid Infrared

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Cosmic biology in perspective

Astrophysics and Space Science ◽

10.1007/s10509-019-3698-6 ◽

2019 ◽

Vol 364 (11) ◽

Author(s):

N. C. Wickramasinghe ◽

Dayal T. Wickramasinghe ◽

Christopher A. Tout ◽

John C. Lattanzio ◽

Edward J. Steele

Keyword(s):

Infrared Spectra ◽

Building Blocks ◽

Mid Infrared ◽

Interstellar Clouds ◽

Astronomical Observations ◽

Habitable Planets ◽

Biologically Relevant ◽

The Galaxy ◽

Terrestrial Life ◽

Biologically Relevant Molecules

AbstractA series of astronomical observations obtained over the period 1986 to 2018 supports the idea that life is a cosmic rather than a purely terrestrial or planetary phenomenon. These include (1) the detection of biologically relevant molecules in interstellar clouds and in comets, (2) mid-infrared spectra of interstellar grains and the dust from comets, (3) a diverse set of data from comets including the Rosetta mission showing consistency with biology and (4) the frequency of Earth-like or habitable planets in the Galaxy. We argue that the conjunction of all the available data suggests the operation of cometary biology and interstellar panspermia rather than the much weaker hypothesis of comets being only the source of the chemical building blocks of life. We conclude with specific predictions on the properties expected of extra-terrestrial life if it is discovered on Enceladus, Europa or beyond. A radically different biochemistry elsewhere can be considered as a falsification of the theory of interstellar panspermia.

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Thermal dynamic imaging of mid-infrared quantum cascade lasers with high temporal–spatial resolution

Journal of Applied Physics ◽

10.1063/5.0013344 ◽

2020 ◽

Vol 128 (8) ◽

pp. 083106 ◽

Cited By ~ 1

Author(s):

Siyi Wang ◽

Chao Xu ◽

Fei Duan ◽

Boyu Wen ◽

S. M. Shazzad Rassel ◽

...

Keyword(s):

Spatial Resolution ◽

Quantum Cascade Lasers ◽

Dynamic Imaging ◽

Mid Infrared ◽

Quantum Cascade ◽

Cascade Lasers

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Combining high spectral and spatial resolution in the mid-infrared

10.1117/12.390255 ◽

2000 ◽

Author(s):

John D. Monnier ◽

William C. Danchi ◽

David D. S. Hale ◽

Peter G. Tuthill ◽

Charles H. Townes

Keyword(s):

Spatial Resolution ◽

Mid Infrared

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UCHII regions in the Antennae

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002645 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 476-476

Author(s):

L. Snijders ◽

L. J. Kewley ◽

P. P. van der Werf ◽

B. R. Brandl

Keyword(s):

Emission Line ◽

Spatial Resolution ◽

Average Density ◽

Physical Characteristics ◽

Stellar Clusters ◽

Mid Infrared ◽

Infrared Observations ◽

Star Forming ◽

Compact Material ◽

Star Forming Regions

AbstractWe explore the physical characteristics of young stellar clusters in the Antennae by combining recent ground- and space-based mid-infrared observations with a newly developed set of diagnostic diagrams. Spitzer data give an overview of the star-forming regions extending over hundreds of parsecs, showing a dominant diffuse ISM component with a density of 102 cm−3 plus a small fraction of very compact material (106 cm−3). With its higher spatial resolution VISIR gives a close-up view of the latter component. Its emission line ratios suggest that these regions are fundamentally different from local star-forming regions. Instead of having small isolated UCHII regions, as in local star-forming regions, the average density of the medium of the whole region falls in the (ultra)compact regime, exceeding 104 cm−3 over tens of parsecs.

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