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Author: Publisher: ISBN: Category : Languages : en Pages : 47
Book Description
The science goals for future ground-based all-sky surveys, such as the Dark Energy Survey, PanSTARRS, and the Large Synoptic Survey Telescope, require calibration of broadband photometry that is stable in time and uniform over the sky to precisions of a per cent or better, and absolute calibration of color measurements that are similarly accurate. This performance will need to be achieved with measurements made from multiple images taken over the course of many years, and these surveys will observe in less than ideal conditions. This paper describes a technique to implement a new strategy to directly measure variations of atmospheric transmittance at optical wavelengths and application of these measurements to calibration of ground-based observations. This strategy makes use of measurements of the spectra of a small catalog of bright 'probe' stars as they progress across the sky and back-light the atmosphere. The signatures of optical absorption by different atmospheric constituents are recognized in these spectra by their characteristic dependences on wavelength and airmass. State-of-the-art models of atmospheric radiation transport and modern codes are used to accurately compute atmospheric extinction over a wide range of observing conditions. We present results of an observing campaign that demonstrate that correction for extinction due to molecular constituents and aerosols can be done with precisions of a few millimagnitudes with this technique.
Author: Publisher: ISBN: Category : Languages : en Pages : 47
Book Description
The science goals for future ground-based all-sky surveys, such as the Dark Energy Survey, PanSTARRS, and the Large Synoptic Survey Telescope, require calibration of broadband photometry that is stable in time and uniform over the sky to precisions of a per cent or better, and absolute calibration of color measurements that are similarly accurate. This performance will need to be achieved with measurements made from multiple images taken over the course of many years, and these surveys will observe in less than ideal conditions. This paper describes a technique to implement a new strategy to directly measure variations of atmospheric transmittance at optical wavelengths and application of these measurements to calibration of ground-based observations. This strategy makes use of measurements of the spectra of a small catalog of bright 'probe' stars as they progress across the sky and back-light the atmosphere. The signatures of optical absorption by different atmospheric constituents are recognized in these spectra by their characteristic dependences on wavelength and airmass. State-of-the-art models of atmospheric radiation transport and modern codes are used to accurately compute atmospheric extinction over a wide range of observing conditions. We present results of an observing campaign that demonstrate that correction for extinction due to molecular constituents and aerosols can be done with precisions of a few millimagnitudes with this technique.
Author: Atmospheric Optics Group Publisher: ISBN: Category : Light absorption Languages : en Pages : 154
Book Description
The primary goals of this project for JTO and ONR (Grant N00014-07-1-1060) were to further develop Extinction Imagers for use in the ocean environment, and to extend the capabilities into the Short Wave IR (SWIR). Extinction Imaging is a method for determining the effective extinction coefficient over an extended path using a sensor at one end of the path. It uses calibrated imagers to acquire the relative radiance of a dark target near the other the end of the path and the horizon sky in the direction of the dark target. It is completely passive and thus covert, and the hardware is robust and relatively inexpensive. It uses rigorous equations, which determine the extinction coefficient from the measured apparent contrast of the radiance of the dark target with respect to the horizon sky. The project was very successful. We found that the ocean surface could readily be used as a dark target in red and SWIR wavelengths. Both the red and the SWIR measurement results were excellent for daytime. Comparisons with standard instruments, as well as uncertainty analysis, indicated that extinction imagers provide better measurements of the atmospheric extinction losses over extended paths than other methods of which we are aware. Our secondary goals were to address the night regime, and to address slanted paths above the horizontal. Regarding night, we found that the visible sensor acquired excellent data, but the ocean surface was not a good dark target in our wavelengths. Recommendations on the handling of night are given in the report. Regarding the lines of sight above the horizon, we developed a slant path algorithm that determines beam transmittance. It performed very well. Recommendations are made regarding integration of these techniques for military applications
Author: Publisher: ScholarlyEditions ISBN: 146496369X Category : Science Languages : en Pages : 2981
Book Description
Issues in Astronomy and Astrophysics / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Astronomy and Astrophysics. The editors have built Issues in Astronomy and Astrophysics: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Astronomy and Astrophysics in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Astronomy and Astrophysics: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Author: Marc F. M. Trypsteen Publisher: Cambridge University Press ISBN: 1316738825 Category : Science Languages : en Pages : 167
Book Description
This accessible guide presents the astrophysical concepts behind astronomical spectroscopy, covering both the theory and the practical elements of recording, processing, analysing and interpreting your spectra. It covers astronomical objects, such as stars, planets, nebulae, novae, supernovae, and events such as eclipses and comet passages. Suitable for anyone with only a little background knowledge and access to amateur-level equipment, the guide's many illustrations, sketches and figures will help you understand and practise this scientifically important and growing field of amateur astronomy, up to the level of Pro-Am collaborations. Accessible to non-academics, it benefits many groups from novices and learners in astronomy clubs, to advanced students and teachers of astrophysics. This volume is the perfect companion to the Spectral Atlas for Amateur Astronomers, which provides detailed commented spectral profiles of more than 100 astronomical objects.
Author: Naval Research Laboratory (U.S.). Optical Radiation Branch Publisher: ISBN: Category : Laser beams Languages : en Pages : 82
Book Description
The NRL Infrared Mobile Optical Radiation Laboratory (IMORL) consisting of various infrared laser sources, large-aperture collimating optics, and precision calibrated infrared detectors and electronics was operated in conjunction with the JAN Baseline Demonstration Laser propagation tests during June-September 1975. The trailer-housed elements of the IMORL unit were deployed so as to use an atmospheric measurement path about 5 km long between the TRW Capistrano Test Site and Camp Pendleton Marine Base. Extensive measurements of atmospheric transmission at several DF laser wavelengths between 3.6 and 4.1 micrometers were obtained as well as measurements at the Nd-YAG laser wavelength of 1.06 micrometers. The optical measurements were supported by meteorological observations near the IMORL transmitter and receiver sites. Atmospheric aerosol distributions were monitored during the experiments, and Mie scattering calculations were performed using the aerosol data and were compared to aerosol extinction values derived from the optical measurements obtained using the 5-km-long path. The water-vapor dependence of molecular absorption for each of the 22 DF laser lines studied was compared to values obtained during earlier experiments at the Cape Canaveral Air Force Station and to theoretical predictions based on a HI-TRAN calculation using a line atlas. The experimental apparatus used (IMORL facility) and the measurements procedures followed are briefly described. The measurement results obtained and their comparisons to theoretical predictions for molecular absorption and aerosol scattering at DF laser wavelengths are presented and discussed. (Author).
Author: Thomas Foken Publisher: Springer Nature ISBN: 3030521710 Category : Science Languages : en Pages : 1761
Book Description
This practical handbook provides a clearly structured, concise and comprehensive account of the huge variety of atmospheric and related measurements relevant to meteorologists and for the purpose of weather forecasting and climate research, but also to the practitioner in the wider field of environmental physics and ecology. The Springer Handbook of Atmospheric Measurements is divided into six parts: The first part offers instructive descriptions of the basics of atmospheric measurements and the multitude of their influencing factors, fundamentals of quality control and standardization, as well as equations and tables of atmospheric, water, and soil quantities. The subsequent parts present classical in-situ measurements as well as remote sensing techniques from both ground-based as well as airborn or satellite-based methods. The next part focusses on complex measurements and methods that integrate different techniques to establish more holistic data. Brief discussions of measurements in soils and water, at plants, in urban and rural environments and for renewable energies demonstrate the potential of such applications. The final part provides an overview of atmospheric and ecological networks. Written by distinguished experts from academia and industry, each of the 64 chapters provides in-depth discussions of the available devices with their specifications, aspects of quality control, maintenance as well as their potential for the future. A large number of thoroughly compiled tables of physical quantities, sensors and system characteristics make this handbook a unique, universal and useful reference for the practitioner and absolutely essential for researchers, students, and technicians.
Author: G. H. Goedecke Publisher: ISBN: Category : Languages : en Pages : 29
Book Description
Several model aerosols of a given type, having the same visibility, but different yet reasonable microstructure, exhibit very wide dispersion, as much as 700%, in values of transmission at wavelengths from 2.0 to 10.6 micrometers. At near infrared wavelengths, from the visible to 2.0 micrometers, the dispersion is reduced, to a tolerable value of 10% at 1.06 micrometers. Two methods are suggested for exploiting the theoretical predictive techniques reported here. Results of a study designed to determine some of the effects of multiple scattering in low visibility situations (fog and a haze-soot mixture) indicate that laser system detectors of small solid angle register a transmission given very accurately by the single-scattering exponential transmission law, even for optical thickness greater than unity, but that detectors of large solid angle observe a considerably enhanced transmission for such optical depths. Also reported are results of two relevant but peripheral investigations, one concerning the application of dispersion relations to the complex reflectivity, the other concerning a necessary modification of radiative transfer theory under certain circumstances.
Author: Shunlin Liang Publisher: Academic Press ISBN: 0123859557 Category : Science Languages : en Pages : 821
Book Description
Advanced Remote Sensing is an application-based reference that provides a single source of mathematical concepts necessary for remote sensing data gathering and assimilation. It presents state-of-the-art techniques for estimating land surface variables from a variety of data types, including optical sensors such as RADAR and LIDAR. Scientists in a number of different fields including geography, geology, atmospheric science, environmental science, planetary science and ecology will have access to critically-important data extraction techniques and their virtually unlimited applications. While rigorous enough for the most experienced of scientists, the techniques are well designed and integrated, making the book’s content intuitive, clearly presented, and practical in its implementation. Comprehensive overview of various practical methods and algorithms Detailed description of the principles and procedures of the state-of-the-art algorithms Real-world case studies open several chapters More than 500 full-color figures and tables Edited by top remote sensing experts with contributions from authors across the geosciences
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Author: Atmospheric Optics Group
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Author: Marc F. M. Trypsteen
Author: Naval Research Laboratory (U.S.). Optical Radiation Branch
Author: Thomas Foken
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Author: G. H. Goedecke
Author: Shunlin Liang![The Theoretical Simulation of Near Infrared Atmospheric Extinction [microform] PDF](https://books.google.com/books/content/images/frontcover/ijT_ygAACAAJ?fife=w80-h100)
Author: Kevin Michael Volk