Suchergebnisse

Intro -- FrontMatter -- Preface -- Acknowledgment of Reviewers -- Contents -- Summary -- 1 Introduction -- 2 Active Earth Remote Sensing for Atmospheric Applications -- 3 Active Earth Remote Sensing for Ocean Applications -- 4 Active Earth Remote Sensing for Land Surface Applications -- 5 Active Earth Remote Sensing for Space Physics -- 6 Planetary Radar Astronomy -- 7 Spectrum Access: Allocation Policies and the Assignment Process -- 8 Radio-Frequency Interference Issues for Active Sensing Instruments -- 9 Technology and the Opportunities for Interference Mitigation -- Appendixes -- Appendix A: Statement of Task -- Appendix B: Committee Meeting and Workshop Agendas -- Appendix C: Summary of the Radio-Frequency Interference Workshop -- Appendix D: Acronyms

Astronomy is a deeply cultural science; an evening spent under a dark, starry night sky can evoke feelings of awe, wonder, and of being a global citizen. On the other hand, the pursuit of astronomical knowledge depends on cross-border co-operation: observers need shared infrastructure and intelligence to study the Universe's greatest mysteries. Not only does this advance science, but also brings significant societal and political benefits: through international collaboration, astronomy can bring governments and nations together to foster trust, peace and prosperity, and to help bridge the North-South divide. In turn, many astronomers themselves are rooted in a culture of openness, devoted to reaching and supporting marginalised communities and narrowing societal gaps. Together, through embracing the mystery of the Universe, we can draw forth upon our empathy and compassion, and come together under one sky.

Proceeding of: 4th International Electronic Conference on Sensors and Applications (ECSA-4) ; Spatial localization of emitting sources is especially interesting in different fields of application. The focus of an earthquake, the determination of cracks in solid structures or the position of bones inside a body are some examples of the use of multilateration techniques applied to acoustic and vibratory signals. Radar, GPS and wireless sensors networks location are based on radiofrequency emissions and the techniques are the same as in the case of acoustic emissions. This paper is focused on the determination of the position of sources of partial discharges inside electrical insulation for maintenance based on the condition of the electrical machine. The use of this phenomenon is a mere example of the capabilities of the proposed method because its emission can be electromagnetic in the UHF range or acoustic when the insulation is immersed in oil. Generally, when a pulse is radiated from a source, the wave will arrive to two receivers at different times. One of the advantages of measuring these time differences of arrival or TDOA is that it is not required a common clock as in other localization techniques based on the time of arrival (TOA) of the pulse to the receiver. With only two sensors, all the possible points in the plane that would give the same TDOA describe a hyperbola. Using an independent third receiver and calculating the intersection of the three hyperbolas will give the position of the source. Therefore, planar localization of emitters using multilateration techniques can be solved at least with three receivers. This paper presents a method to locate sources in a plane with only two receivers, one of them in a fixed position and the other is placed describing a circumference around the first one. The TDOA are measured at different angles completing a total turn and obtaining a function, angle versus TDOA, that has all the geometric information needed to locate the source. ; The work done in this paper has been funded by the Spanish Government under contract DPI2015-66478-C2-1-R (MINECO/FEDER, UE)

We present amultiwavelength study of IC 1531 (z=0.02564), an extragalactic radio source associated with the γ -ray object 3FGL J0009.9-3206 and classified as a blazar of uncertain type in the Third Fermi-Large Area Telescope AGN catalog (3LAC). A core-jet structure, visible in radio and X-rays, is enclosed within a ~220 kpc wide radio structure. The morphology and spectral characteristics of the kiloparsec jet in radio and X-rays are typical of Fanaroff-Riley type I galaxies. The analysis of the radio data and optical spectrum and different diagnostic methods based on the optical, infrared, and γ -ray luminosities also support a classification as a low-power RG seen at moderate angles (θ = 10°-20°). In the framework of leptonic models, the high-energy peak of the non-thermal nuclear spectral energy distribution can be explained in terms of synchrotron-self-Compton emission from a jet seen at θ ~ 15°. Similarly to other misaligned AGNs detected by Fermi, the required bulk motion is lower (Γ = 4) than the values inferred in BL Lac objects, confirming that, because of the de-boosting of emission from the highly relativistic blazar region, these nearby systems are valuable targets to probe the existence of multiple sites of production of the most energetic emission in the jets.© 2018 The Author(s). ; The research leading to these results has received funding from the European Union's Horizon 2020 Programme under AHEAD project (grant agreement n. 654215). Partial support to this work was provided by the NASA grant AR4-15009X. GM acknowledges the financial support from the UnivEarthS Labex program of Sorbonne Paris Cite (ANR10LABX0023 and ANR11IDEX000502). We thank the anonymous referee for comments and suggestions that helped us to improve the manuscript. TB acknowledges financial contribution from the agreement ASI-INAF n. 2017-14-H.0. MAPT acknowledges support from the Spanish MINECO through grants AYA2012-38491-C02-02 and AYA2015-63939-C2-1-P. AS was supported by NASA contract NAS8-03060 (Chandra X-ray Center). ET acknowledges financial support from ASI-INAF grant 2015-023-R.O. We acknowledge financial support from PRIN INAF 2016. This work has used data supplied by the UK Swift Science Data Centre at the University of Leicester and archival data from the VLA. The NRAO a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

En el campo de la radioastronomía los amplificadores de bajo ruido (LNA, Low Noise Amplifier) constituyen la etapa encargada de aportar a las señales detectadas la potencia necesaria para que puedan ser adecuadamente manejadas en etapas posteriores. Se describe el proceso de diseño, fabricación y caracterización de un LNA que ha de funcionar enfriado criogénicamente. El marco de aplicación del sistema es la fabricación de una cadena de detección de prueba compacta, encaminada a experimentar con la tecnología que permita el futuro desarrollo de un detector bidimensional multipixel para aplicaciones radioastronómicas. El trabajo desarrollado se enmarca dentro del proyecto AMSTAR+ (Radionet-FP7) financiado por la Unión Europea, y ha sido realizado íntegramente en el prestigioso Centro Astronómico de Yebes (CAY) situado en la localidad de Yebes (Guadalajara, Castilla la Mancha). [ABSTRACT] In the field of radio astronomy, low noise amplifiers (LNA) are the stages which provide power to the detected signals so these can be adequately managed by subsequent stages. The process of design, construction and measurement of a cryogenic LNA is described. The application framework for this design is the development of a test detection chain that can be used to experiment with the technology that will allow development of a bi-dimensional multipixel detector for radio astronomy purposes. This work has been developed within the framework of the AMSTAR+ project (Radionet-FP7) financed by the European Union and been carried out entirely at the prestigious Yebes Astronomy Center (CAY, Centro Astronómico de Yebes) located in Yebes (Guadalajara, Castilla la Mancha,Spain).