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18 results on '"Avruch, Ian M."'

1. Deep reinforcement learning for smart calibration of radio telescopes

Author

Yatawatta, Sarod and Avruch, Ian M.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Computer Science - Artificial Intelligence, Computer Science - Machine Learning
Abstract

Modern radio telescopes produce unprecedented amounts of data, which are passed through many processing pipelines before the delivery of scientific results. Hyperparameters of these pipelines need to be tuned by hand to produce optimal results. Because many thousands of observations are taken during a lifetime of a telescope and because each observation will have its unique settings, the fine tuning of pipelines is a tedious task. In order to automate this process of hyperparameter selection in data calibration pipelines, we introduce the use of reinforcement learning. We test two reinforcement learning techniques, twin delayed deep deterministic policy gradient (TD3) and soft actor-critic (SAC), to train an autonomous agent to perform this fine tuning. For the sake of generalization, we consider the pipeline to be a black-box system where the summarized state of the performance of the pipeline is used by the autonomous agent. The autonomous agent trained in this manner is able to determine optimal settings for diverse observations and is therefore able to perform 'smart' calibration, minimizing the need for human intervention., Comment: MNRAS Accepted 2021 May 12. Received 2021 May 11; in original form 2021 February 5

Published
2021
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3. The LOFAR long baseline snapshot calibrator survey

Author

Moldon, J, Morabito, Leah K., Avruch, Ian M., Bernardi, G, Breitling, F, Brüggen, M, Butcher, Harvey, Ciardi, Benedetta, de Gasperin, F, Engels, Dieter, Falcke, H, Hoeft, M, Kuniyoshi, M, Mann, Gottfried, Offringa, Andre, Reich, W, Vocks, Christian, Moldon, J, Morabito, Leah K., Avruch, Ian M., Bernardi, G, Breitling, F, Brüggen, M, Butcher, Harvey, Ciardi, Benedetta, de Gasperin, F, Engels, Dieter, Falcke, H, Hoeft, M, Kuniyoshi, M, Mann, Gottfried, Offringa, Andre, Reich, W, and Vocks, Christian

Abstract

Aims. An efficient means of locating calibrator sources for international LOw Frequency ARray (LOFAR) is developed and used to determine the average density of usable calibrator sources on the sky for subarcsecond observations at 140 MHz. Methods. We used the multi-beaming capability of LOFAR to conduct a fast and computationally inexpensive survey with the full international LOFAR array. Sources were preselected on the basis of 325 MHz arcminute-scale flux density using existing catalogues. By observing 30 different sources in each of the 12 sets of pointings per hour, we were able to inspect 630 sources in two hours to determine if they possess a sufficiently bright compact component to be usable as LOFAR delay calibrators. Results. More than 40% of the observed sources are detected on multiple baselines between international stations and 86 are classified as satisfactory calibrators. We show that a flat low-frequency spectrum (from 74 to 325 MHz) is the best predictor of compactness at 140 MHz. We extrapolate from our sample to show that the sky density of calibrators that are sufficiently bright to calibrate dispersive and non-dispersive delays for the international LOFAR using existing methods is 1.0 per square degree. Conclusions. The observed density of satisfactory delay calibrator sources means that observations with international LOFAR should be possible at virtually any point in the sky provided that a fast and efficient search, using the methodology described here, is conducted prior to the observation to identify the best calibrator.

Published
2015

4. The shape of the radio wavefront of extensive air showers as measured with LOFAR

Author

Butcher, Harvey, Frieswijk, W, Scholten, O, Bentum, M J, Bernardi, G, Bonafede, A, Ciardi, Benedetta, de Gasperin, F, Duscha, S, Fallows, R A, Garrett, M A, Gunst, A W, Hoeft, M, Kondratiev, V. I., Kuniyoshi, M, Maat, P, Norden, M J, Pizzo, R, Polatidis, A.G., Reich, W, Vermeulen, R.C., Wijnholds, S J, Yatawatta, S, Avruch, Ian M., Breitling, F, de Geus, Eugene, de Vos, Marco, Engels, Dieter, Hamaker, Johan P., Iacobelli, M., Kuper, G., Munk, H, Toribio, C., Vocks, Christian, Butcher, Harvey, Frieswijk, W, Scholten, O, Bentum, M J, Bernardi, G, Bonafede, A, Ciardi, Benedetta, de Gasperin, F, Duscha, S, Fallows, R A, Garrett, M A, Gunst, A W, Hoeft, M, Kondratiev, V. I., Kuniyoshi, M, Maat, P, Norden, M J, Pizzo, R, Polatidis, A.G., Reich, W, Vermeulen, R.C., Wijnholds, S J, Yatawatta, S, Avruch, Ian M., Breitling, F, de Geus, Eugene, de Vos, Marco, Engels, Dieter, Hamaker, Johan P., Iacobelli, M., Kuper, G., Munk, H, Toribio, C., and Vocks, Christian

Abstract

Extensive air showers, induced by high energy cosmic rays impinging on the Earth's atmosphere, produce radio emission that is measured with the LOFAR radio telescope. As the emission comes from a finite distance of a few kilometers, the incident wavefront is non-planar. A spherical, conical or hyperbolic shape of the wavefront has been proposed, but measurements of individual air showers have been inconclusive so far. For a selected high-quality sample of 161 measured extensive air showers, we have reconstructed the wavefront by measuring pulse arrival times to sub-nanosecond precision in 200 to 350 individual antennas. For each measured air shower, we have fitted a conical, spherical, and hyperboloid shape to the arrival times. The fit quality and a likelihood analysis show that a hyperboloid is the best parameterization. Using a non-planar wavefront shape gives an improved angular resolution, when reconstructing the shower arrival direction. Furthermore, a dependence of the wavefront shape on the shower geometry can be seen. This suggests that it will be possible to use a wavefront shape analysis to get an additional handle on the atmospheric depth of the shower maximum, which is sensitive to the mass of the primary particle.

Published
2015

5. Probing atmospheric electric fields in thunderstorms through radio emission from cosmic-ray-induced air showers

Author

Schellart, P, Trinh, T. N. G., Buitink, S, Corstanje, Arthur, Enriquez, J.E., Falcke, H, Hörandel, J.R., Nelles, A, Rachen, J.P., Rossetto, L, Scholten, O, Ter Veen, Sander, Thoudam, Satyendra, Ebert, U, Koehn, C, Rutjes, C, Alexov, A., Anderson, J M, Avruch, Ian M., Bentum, M J, Bernardi, G, Best, Phillip, Bonafede, A, Breitling, F, Broderick, J, Bruggen, M, Butcher, Harvey, Ciardi, Benedetta, de Geus, Eugene, de Vos, Marco, Duscha, S, Eisloffel, Jochen, Hoeft, M, Holties, H. A, Juette, E, Kondratiev, V. I., Kuniyoshi, M, Kuper, G., Mann, Gottfried, McFadden, R, McKay-Bukowski, D, McKean, J P, Mevius, Maaijke, Moldon, J, Norden, M J, Orru, Emanuela, Paas, H., Pandey-Pommier, Mamta, Pizzo, R, Polatidis, A.G., Reich, W, Rottgering, Hubb, Scaife, Anna, Schwarz, Dominik, Serylak, M, Smirnov, O, Steinmetz, M., Swinbank, J, Tagger, Michel, Tasse, C, van Weeren, Reinout J., Toribio, C., Vermeulen, R.C., Vocks, Christian, Wise, Michael W, Wucknitz, O, Zarka, P, Schellart, P, Trinh, T. N. G., Buitink, S, Corstanje, Arthur, Enriquez, J.E., Falcke, H, Hörandel, J.R., Nelles, A, Rachen, J.P., Rossetto, L, Scholten, O, Ter Veen, Sander, Thoudam, Satyendra, Ebert, U, Koehn, C, Rutjes, C, Alexov, A., Anderson, J M, Avruch, Ian M., Bentum, M J, Bernardi, G, Best, Phillip, Bonafede, A, Breitling, F, Broderick, J, Bruggen, M, Butcher, Harvey, Ciardi, Benedetta, de Geus, Eugene, de Vos, Marco, Duscha, S, Eisloffel, Jochen, Hoeft, M, Holties, H. A, Juette, E, Kondratiev, V. I., Kuniyoshi, M, Kuper, G., Mann, Gottfried, McFadden, R, McKay-Bukowski, D, McKean, J P, Mevius, Maaijke, Moldon, J, Norden, M J, Orru, Emanuela, Paas, H., Pandey-Pommier, Mamta, Pizzo, R, Polatidis, A.G., Reich, W, Rottgering, Hubb, Scaife, Anna, Schwarz, Dominik, Serylak, M, Smirnov, O, Steinmetz, M., Swinbank, J, Tagger, Michel, Tasse, C, van Weeren, Reinout J., Toribio, C., Vermeulen, R.C., Vocks, Christian, Wise, Michael W, Wucknitz, O, and Zarka, P

Abstract

We present measurements of radio emission from cosmic ray air showers that took place during thunderstorms. The intensity and polarization patterns of these air showers are radically different from those measured during fair-weather conditions. With the use of a simple two-layer model for the atmospheric electric field, these patterns can be well reproduced by state-of-the-art simulation codes. This in turn provides a novel way to study atmospheric electric fields.

Published
2015

6. LOFAR tied-array imaging and spectroscopy of solar S bursts

Author

Morosan, D E, Gallagher, P T, Zucca, P, O’Flannagain, A, Fallows, R A, Reid, H, Magdalenic, J, Mann, Gottfried, Hoeft, M, Bisi, M M, Butcher, Harvey, Konovalenko, A A, Vocks, Christian, Avruch, Ian M., Bernardi, G, Bonafede, A, Breitling, F, Brouw, W. N., Ciardi, Benedetta, Falcke, H, Morosan, D E, Gallagher, P T, Zucca, P, O’Flannagain, A, Fallows, R A, Reid, H, Magdalenic, J, Mann, Gottfried, Hoeft, M, Bisi, M M, Butcher, Harvey, Konovalenko, A A, Vocks, Christian, Avruch, Ian M., Bernardi, G, Bonafede, A, Breitling, F, Brouw, W. N., Ciardi, Benedetta, and Falcke, H

Abstract

The Sun is an active source of radio emission that is often associated with energetic phenomena ranging from nanoflares to coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), numerous millisecond duration radio bursts have been reported, such as radio spikes or solar S bursts (where S stands for short). To date, these have neither been studied extensively nor imaged because of the instrumental limitations of previous radio telescopes. Aims. Here, LOw Frequency ARray (LOFAR) observations were used to study the spectral and spatial characteristics of a multitude of S bursts, as well as their origin and possible emission mechanisms. Methods. We used 170 simultaneous tied-array beams for spectroscopy and imaging of S bursts. Since S bursts have short timescales and fine frequency structures, high cadence (~50 ms) tied-array images were used instead of standard interferometric imaging, that is currently limited to one image per second. Results. On 9 July 2013, over 3000 S bursts were observed over a time period of ~8 h. S bursts were found to appear as groups of short-lived (<1 s) and narrow-bandwidth (~2.5 MHz) features, the majority drifting at ~3.5 MHzs-1 and a wide range of circular polarisation degrees (2-8 times more polarised than the accompanying Type III bursts). Extrapolation of the photospheric magnetic field using the potential field source surface (PFSS) model suggests that S bursts are associated with a trans-equatorial loop system that connects an active region in the southern hemisphere to a bipolar region of plage in the northern hemisphere. Conclusions. We have identified polarised, short-lived solar radio bursts that have never been imaged before. They are observed at a height and frequency range where plasma emission is the dominant emission mechanism, however, they possess some of the characteristics of electron-cyclotron maser emission.

Published
2015

7. Water masers in the Kronian system

Author

Pogrebenko, Sergei V., Gurvits, Leonid I., Elitzur, Moshe, Cosmovici, Cristiano B., Avruch, Ian M., Pluchino, Salvatore, Montebugnoli, Stelio, Salerno, Emma, Maccaferri, Giuseppe, Mujunen, Ari, Ritakari, Jouko, Molera, Guifre, Wagner, Jan, Uunila, Minttu, Cimo, Giuseppe, Schilliro, Francesco, Bartolini, Marco, Fernández, J. A., Lazzaro, D., Prialnik, D., Schulz, R., and Astronomy

Subjects
molecular data, Space and Planetary Science, masers, Astronomy and Astrophysics, Planets and satellites
Abstract

The presence of water has been considered for a long time as a key condition for life in planetary environments. The Cassini mission discovered water vapour in the Kronian system by detecting absorption of UV emission from a background star (Hansen et al. 2006). Prompted by this discovery, we started an observational campaign for search of another manifestation of the water vapour in the Kronian system, its maser emission at the frequency of 22 GHz (1.35 cm wavelength). Observations with the 32 m Medicina radio telescope (INAF-IRA, Italy) started in 2006 using Mk5A data recording and the JIVE-Huygens software correlator. Later on, an on-line spectrometer was used at Medicina. The 14 m Metsähovi radio telescope (TKK-MRO, Finland) joined the observational campaign in 2008 using a locally developed data capture unit and software spectrometer. More than 300 hours of observations were collected in 2006-2008 campaign with the two radio telescopes. The data were analysed at JIVE using the Doppler tracking technique to compensate the observed spectra for the radial Doppler shift for various bodies in the Kronian system (Pogrebenko et al. 2009). Here we report the observational results for Hyperion, Titan, Enceladus and Atlas, and their physical interpretation. Encouraged by these results we started a campaign of follow up observations including other radio telescopes.

Published
2010

8. Initial LOFAR observations of epoch of reionization windows: II. diffuse polarized emission in the ELAIS-N1 field

Author

Jelic, VIBOR, de Bruyn, A.G., Brentjens, Michiel A, Ciardi, Benedetta, Ghosh, A., Koopmans, L. V. E., Bonafede, A, Offringa, Andre, Brouw, W. N., de Gasperin, F, Butcher, Harvey, Falcke, H, Hoeft, M, Kuniyoshi, M, Reich, W, Avruch, Ian M., Breitling, F, Engels, Dieter, Iacobelli, M., Mann, Gottfried, Vocks, Christian, Jelic, VIBOR, de Bruyn, A.G., Brentjens, Michiel A, Ciardi, Benedetta, Ghosh, A., Koopmans, L. V. E., Bonafede, A, Offringa, Andre, Brouw, W. N., de Gasperin, F, Butcher, Harvey, Falcke, H, Hoeft, M, Kuniyoshi, M, Reich, W, Avruch, Ian M., Breitling, F, Engels, Dieter, Iacobelli, M., Mann, Gottfried, and Vocks, Christian

Abstract

Aims. This study aims to characterise the polarized foreground emission in the ELAIS-N1 field and to address its possible implications for extracting of the cosmological 21 cm signal from the LOw-Frequency ARray-Epoch of Reionization (LOFAR-EoR) data. Methods. We used the high band antennas of LOFAR to image this region and RM-synthesis to unravel structures of polarized emission at high Galactic latitudes. Results. The brightness temperature of the detected Galactic emission is on average ~4 K in polarized intensity and covers the range from-10 to + 13 rad m-2 in Faraday depth. The total polarized intensity and polarization angle show a wide range of morphological features. We have also used the Westerbork Synthesis Radio Telescope (WSRT) at 350 MHz to image the same region. The LOFAR and WSRT images show a similar complex morphology at comparable brightness levels, but their spatial correlation is very low. The fractional polarization at 150 MHz, expressed as a percentage of the total intensity, amounts to 1.5%. There is no indication of diffuse emission in total intensity in the interferometric data, in line with results at higher frequencies Conclusions. The wide frequency range, high angular resolution, and high sensitivity make LOFAR an exquisite instrument for studying Galactic polarized emission at a resolution of ~1-2 rad m-2 in Faraday depth. The different polarized patterns observed at 150 MHz and 350 MHz are consistent with different source distributions along the line of sight wring in a variety of Faraday thin regions of emission. The presence of polarized foregrounds is a serious complication for epoch of reionization experiments. To avoid the leakage of polarized emission into total intensity, which can depend on frequency, we need to calibrate the instrumental polarization across the field of view to a small fraction of 1%.

Published
2014

9. Discovery of carbon radio recombination lines in absorption towards Cygnus A

Author

Oonk, J. B. R., van Weeren, R. J., Salgado, Francisco, Morabito, Leah K., Tielens, Alexander G. G. M., Rottgering, Hubb, Asgekar, A, White, Glenn J., Alexov, A., Anderson, J. M., Avruch, Ian M., Batejat, F., Beck, Rainer, Bell, M. E., van Bemmel, Illse, Bentum, M. J., Bernardi, Gianni, Best, Phillip, Bonafede, A., Breitling, F., Brentjens, Michiel A., Broderick, J., Bruggen, M, Butcher, Harvey, Ciardi, Benedetta, Conway, J. E., Corstanje, Arthur, de Gasperin, F., de Geus, Eugene, de Vos, Marco, Duscha, S., Eisloffel, Jochen, Engels, Dieter, Van Enst, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Grießmeier, J., Hamaker, Johan P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Horneffer, Andreas, Van Der Horst, Alexander, Iacobelli, M., Jackson, Neal, Juette, E., Karastergiou, A., Klijn, W., Kohler, Jens, Kondratiev, V. I., Kramer, M, Kuniyoshi, M, Kuper, G., van Leeuwen, J, Maat, P, Macario, Giulia, Mann, Gottfried, Markoff, Sera, McKean, J P, Mevius, Maaijke, Miller-Jones, J. C. A., Mol, J. D., Mulcahy, D.D., Munk, H, Norden, M J, Orru, Emanuela, Paas, H., Pandey-Pommier, Mamta, Pandey, V N, Pizzo, R, Polatidis, A.G., Reich, W, Scaife, Anna, Schoenmakers, Arno, Schwarz, Dominik, Shulevski, Alexander, Sluman, J, Smirnov, O, Sobey, C, Stappers, B. W., Steinmetz, M., Swinbank, J, Tagger, Michel, Tang, Y, Tasse, C, Ter Veen, Sander, Thoudam, Satyendra, Toribio, C., Van Nieuwpoort, Rob, Vermeulen, R.C., Vocks, Christian, Yatawatta, S, Oonk, J. B. R., van Weeren, R. J., Salgado, Francisco, Morabito, Leah K., Tielens, Alexander G. G. M., Rottgering, Hubb, Asgekar, A, White, Glenn J., Alexov, A., Anderson, J. M., Avruch, Ian M., Batejat, F., Beck, Rainer, Bell, M. E., van Bemmel, Illse, Bentum, M. J., Bernardi, Gianni, Best, Phillip, Bonafede, A., Breitling, F., Brentjens, Michiel A., Broderick, J., Bruggen, M, Butcher, Harvey, Ciardi, Benedetta, Conway, J. E., Corstanje, Arthur, de Gasperin, F., de Geus, Eugene, de Vos, Marco, Duscha, S., Eisloffel, Jochen, Engels, Dieter, Van Enst, J., Falcke, H., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Grießmeier, J., Hamaker, Johan P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Horneffer, Andreas, Van Der Horst, Alexander, Iacobelli, M., Jackson, Neal, Juette, E., Karastergiou, A., Klijn, W., Kohler, Jens, Kondratiev, V. I., Kramer, M, Kuniyoshi, M, Kuper, G., van Leeuwen, J, Maat, P, Macario, Giulia, Mann, Gottfried, Markoff, Sera, McKean, J P, Mevius, Maaijke, Miller-Jones, J. C. A., Mol, J. D., Mulcahy, D.D., Munk, H, Norden, M J, Orru, Emanuela, Paas, H., Pandey-Pommier, Mamta, Pandey, V N, Pizzo, R, Polatidis, A.G., Reich, W, Scaife, Anna, Schoenmakers, Arno, Schwarz, Dominik, Shulevski, Alexander, Sluman, J, Smirnov, O, Sobey, C, Stappers, B. W., Steinmetz, M., Swinbank, J, Tagger, Michel, Tang, Y, Tasse, C, Ter Veen, Sander, Thoudam, Satyendra, Toribio, C., Van Nieuwpoort, Rob, Vermeulen, R.C., Vocks, Christian, and Yatawatta, S

Abstract

We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33-57MHz range. These low-frequency radio observations provide us with

Published
2014

10. Initial deep LOFAR observations of epoch of reionization windows: I. The north celestial pole

Author

Yatawatta, S, de Bruyn, A G, Brentjens, Michiel A, Labropoulos, Panos, Pandey, V N, Kazemi, S., Zaroubi, Saleem, Koopmans, L. V. E., Offringa, Andre, Jelic, V, Martinez Rubi, O, Veligatla, V, Wijnholds, S J, Brouw, W. N., Bernardi, G, Ciardi, Benedetta, Daiboo, S, Harker, Geraint, Mellema, G., Bell, M, Bonafede, A, Broderick, J, de Gasperin, F, Hassall, T. E, Hoeft, M, Karastergiou, A, Orru, E, Pandey-Pommier, M, Röttgering, H. J. A, van Weeren, R. J., Schaye, J, Avruch, Ian M., Bell, Michael R, Iacobelli, M., Smirnov, O, Ter Veen, Sander, Yatawatta, S, de Bruyn, A G, Brentjens, Michiel A, Labropoulos, Panos, Pandey, V N, Kazemi, S., Zaroubi, Saleem, Koopmans, L. V. E., Offringa, Andre, Jelic, V, Martinez Rubi, O, Veligatla, V, Wijnholds, S J, Brouw, W. N., Bernardi, G, Ciardi, Benedetta, Daiboo, S, Harker, Geraint, Mellema, G., Bell, M, Bonafede, A, Broderick, J, de Gasperin, F, Hassall, T. E, Hoeft, M, Karastergiou, A, Orru, E, Pandey-Pommier, M, Röttgering, H. J. A, van Weeren, R. J., Schaye, J, Avruch, Ian M., Bell, Michael R, Iacobelli, M., Smirnov, O, and Ter Veen, Sander

Abstract

Aims. The aim of the LOFAR epoch of reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21 cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to

Published
2013

11. Studying Galactic interstellar turbulence through fluctuations in synchrotron emission: First LOFAR Galactic foreground detection

Author

Pizzo, R, Bonafede, A, Heald, G, Kuniyoshi, M, Reich, W, Sobey, C, Asgekar, A, Bentum, M J, Bernardi, G, Best, Phillip, Breitling, F, Broderick, J, Ciardi, Benedetta, de Gasperin, F, Duscha, S, Falcke, H, Fallows, R A, Ferrari, C, Frieswijk, W, Gunst, A W, Hassall, T. E, Hoeft, M, Karastergiou, A, van Leeuwen, J, McKean, J P, Polatidis, A.G., Röttgering, H. J. A, Rottgering, Hubb, Sluman, J, Stappers, B. W., Vermeulen, R.C., Yatawatta, S, Orru, E, Garrett, M A, Hessels, J. W. T., Butcher, Harvey, Kondratiev, V. I., Wise, M J, Haverkorn, Marijke, Alexov, A., Steinmetz, M., Iacobelli, M., Anderson, J M, Beck, Rainer, Bell, Michael R, Mulcahy, D.D., Avruch, Ian M., van Bemmel, Illse, de Geus, Eugene, Engels, Dieter, Hamaker, Johan P., Kuper, G., Mann, Gottfried, Munk, H, Tang, Y, Toribio, C., Vocks, Christian, Pizzo, R, Bonafede, A, Heald, G, Kuniyoshi, M, Reich, W, Sobey, C, Asgekar, A, Bentum, M J, Bernardi, G, Best, Phillip, Breitling, F, Broderick, J, Ciardi, Benedetta, de Gasperin, F, Duscha, S, Falcke, H, Fallows, R A, Ferrari, C, Frieswijk, W, Gunst, A W, Hassall, T. E, Hoeft, M, Karastergiou, A, van Leeuwen, J, McKean, J P, Polatidis, A.G., Röttgering, H. J. A, Rottgering, Hubb, Sluman, J, Stappers, B. W., Vermeulen, R.C., Yatawatta, S, Orru, E, Garrett, M A, Hessels, J. W. T., Butcher, Harvey, Kondratiev, V. I., Wise, M J, Haverkorn, Marijke, Alexov, A., Steinmetz, M., Iacobelli, M., Anderson, J M, Beck, Rainer, Bell, Michael R, Mulcahy, D.D., Avruch, Ian M., van Bemmel, Illse, de Geus, Eugene, Engels, Dieter, Hamaker, Johan P., Kuper, G., Mann, Gottfried, Munk, H, Tang, Y, Toribio, C., and Vocks, Christian

Abstract

Aims. The characteristic outer scale of turbulence (i.e. the scale at which the dominant source of turbulence injects energy to the interstellar medium) and the ratio of the random to ordered components of the magnetic field are key parameters to characte

Published
2013

12. The brightness and spatial distributions of terrestrial radio sources

Author

Offringa, Andre, Butcher, Harvey, de Bruyn, A. G., Zaroubi, Saleem, Koopmans, L. V. E., Wijnholds, S. J., Abdalla, Filipe B., Brouw, W. N., Ciardi, Benedetta, Iliev, I. T., Harker, Geraint, Mellema, G., Bernardi, G., Zarka, P., Ghosh, A., Alexov, A., Anderson, J. M., Asgekar, A., Avruch, Ian M., Bell, Michael R., Bentum, M. J., Breitling, F., de Gasperin, F., de Geus, Eugene, de Vos, Marco, Duscha, S., Fallows, R. A., Frieswijk, W., Garrett, M. A., Iacobelli, M., Klijn, W., Kondratiev, V. I., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Mann, Gottfried, McKean, J. P., Norden, M. J., Pizzo, R., Polatidis, A. G., Rafferty, D. A., Reich, W., Van Nieuwpoort, Rob, Sluman, J., Sobey, C., Tang, Y., Toribio, C., Vermeulen, R. C., Vocks, Christian, Wise, M. J., Offringa, Andre, Butcher, Harvey, de Bruyn, A. G., Zaroubi, Saleem, Koopmans, L. V. E., Wijnholds, S. J., Abdalla, Filipe B., Brouw, W. N., Ciardi, Benedetta, Iliev, I. T., Harker, Geraint, Mellema, G., Bernardi, G., Zarka, P., Ghosh, A., Alexov, A., Anderson, J. M., Asgekar, A., Avruch, Ian M., Bell, Michael R., Bentum, M. J., Breitling, F., de Gasperin, F., de Geus, Eugene, de Vos, Marco, Duscha, S., Fallows, R. A., Frieswijk, W., Garrett, M. A., Iacobelli, M., Klijn, W., Kondratiev, V. I., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Mann, Gottfried, McKean, J. P., Norden, M. J., Pizzo, R., Polatidis, A. G., Rafferty, D. A., Reich, W., Van Nieuwpoort, Rob, Sluman, J., Sobey, C., Tang, Y., Toribio, C., Vermeulen, R. C., Vocks, Christian, and Wise, M. J.

Abstract

Faint undetected sources of radio-frequency interference (RFI) might become visible in long radio observations when they are consistently present over time. Thereby, they might obstruct the detection of the weak astronomical signals of interest. This issu

Published
2013

13. Water masers in the Kronian system

Author

Pogrebenko, Sergei V., primary, Gurvits, Leonid I., additional, Elitzur, Moshe, additional, Cosmovici, Cristiano B., additional, Avruch, Ian M., additional, Pluchino, Salvatore, additional, Montebugnoli, Stelio, additional, Salerno, Emma, additional, Maccaferri, Giuseppe, additional, Mujunen, Ari, additional, Ritakari, Jouko, additional, Molera, Guifre, additional, Wagner, Jan, additional, Uunila, Minttu, additional, Cimo, Giuseppe, additional, Schilliro, Francesco, additional, and Bartolini, Marco, additional

Published
2009
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14. Overview of the coordinated ground-based observations of Titan during the Huygens mission

Author

Witasse, Olivier, primary, Lebreton, Jean-Pierre, additional, Bird, Michael K., additional, Dutta-Roy, Robindro, additional, Folkner, William M., additional, Preston, Robert A., additional, Asmar, Sami W., additional, Gurvits, Leonid I., additional, Pogrebenko, Sergei V., additional, Avruch, Ian M., additional, Campbell, Robert M., additional, Bignall, Hayley E., additional, Garrett, Michael A., additional, van Langevelde, Huib Jan, additional, Parsley, Stephen M., additional, Reynolds, Cormac, additional, Szomoru, Arpad, additional, Reynolds, John E., additional, Phillips, Chris J., additional, Sault, Robert J., additional, Tzioumis, Anastasios K., additional, Ghigo, Frank, additional, Langston, Glen, additional, Brisken, Walter, additional, Romney, Jonathan D., additional, Mujunen, Ari, additional, Ritakari, Jouko, additional, Tingay, Steven J., additional, Dodson, Richard G., additional, van't Klooster, C. G. M., additional, Blancquaert, Thierry, additional, Coustenis, Athena, additional, Gendron, Eric, additional, Sicardy, Bruno, additional, Hirtzig, Mathieu, additional, Luz, David, additional, Negrao, Alberto, additional, Kostiuk, Theodor, additional, Livengood, Timothy A., additional, Hartung, Markus, additional, de Pater, Imke, additional, Ádámkovics, Mate, additional, Lorenz, Ralph D., additional, Roe, Henry, additional, Schaller, Emily, additional, Brown, Michael, additional, Bouchez, Antonin H., additional, Trujillo, Chad A., additional, Buratti, Bonnie J., additional, Caillault, Lise, additional, Magin, Thierry, additional, Bourdon, Anne, additional, and Laux, Christophe, additional

Published
2006
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16. The VLBI Space Observatory Programme and the Radio-Astronomical Satellite HALCA

Author

Hirabayashi, Hisashi, primary, Hirosawa, Haruto, additional, Kobayashi, Hideyuki, additional, Murata, Yasuhiro, additional, Asaki, Yoshiharu, additional, Avruch, Ian M., additional, Edwards, Philip G., additional, Fomalont, Edward B., additional, Ichikawa, Tsutomu, additional, Kii, Tsuneo, additional, Okayasu, Rikako, additional, Wajima, Kiyoaki, additional, Inoue, Makoto, additional, Kawaguchi, Noriyuki, additional, Chikada, Yoshihiro, additional, Bushimata, Takeshi, additional, Fujisawa, Kenta, additional, Horiuchi, Shinji, additional, Kameno, Seiji, additional, Miyaji, Takeshi, additional, Shibata, Kazunori M., additional, Shen, Zhi-Qiang, additional, Umemoto, Tomofumi, additional, Kasuga, Takashi, additional, Nakajima, Jun'ichi, additional, Takahashi, Yukio, additional, Enome, Shinzou, additional, Morimoto, Masaki, additional, Ellis, Jordan, additional, Meier, David L., additional, Murphy, David W., additional, Preston, Robert A., additional, Smith, Joel G., additional, Wietfeldt, Rick D., additional, Benson, John M., additional, Claussen, Mark J., additional, Flatters, Chris, additional, Moellenbrock, George A., additional, Romney, Jonathan D., additional, Ulvestad, James S., additional, Langston, Glen I., additional, Minter, Anthony H., additional, D'Addario, Larry R., additional, Dewdney, Peter E., additional, Dougherty, Sean M., additional, Jauncey, David L., additional, Lovell, James E. J., additional, Tingay, Steven J., additional, Tzioumis, Anastasios K., additional, Taylor, A. Russell, additional, Cannon, Wayne H., additional, Gurvits, Leonid I., additional, Schilizzi, Richard T., additional, Booth, Roy S., additional, and Popov, Misha V., additional

Published
2000
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17. The VSOP 5 GHz AGN Survey I. Compilation and Observations

Author

Hirabayashi, Hisashi, primary, Fomalont, Edward B., additional, Horiuchi, Shinji, additional, Lovell, James E. J., additional, Moellenbrock, George A., additional, Inoue, Makoto, additional, Burke, Bernard F., additional, Dewdney, Peter E., additional, Gurvits, Leonid I., additional, Kobayashi, Hideyuki, additional, Jauncey, David L., additional, Murata, Yasuhiro, additional, McCulloch, Peter, additional, Preston, Robert A., additional, Avruch, Ian M., additional, Edwards, Philip G., additional, Dougherty, Sean M., additional, Scott, William K., additional, Frey, Sandor, additional, Paragi, Zsolt, additional, Kovalev, Yuri A., additional, Popov, Misha, additional, Romney, Jonathan D., additional, Schilizzi, Richard T., additional, Shen, Zhi-Qiang, additional, Nicolson, George, additional, Quick, Jonathan, additional, Costa, Marco, additional, Dodson, Richard, additional, Reynolds, John E., additional, Tzioumis, Anastasios K., additional, Tingay, Steven J., additional, Hong, Xiao-Yu, additional, Liang, Shi-Guang, additional, Huang, Xin-Yong, additional, Wei, Wen-Ren, additional, Trigilio, Corrado, additional, Tuccari, Gino, additional, Nakajima, Jun'ichi, additional, Kawai, Eiji, additional, Umemoto, Tomofumi, additional, Miyaji, Takeshi, additional, Fujisawa, Kenta, additional, Kawaguchi, Noriyuki, additional, Kus, Andrzej, additional, Ghigo, Frank, additional, Salter, Chris, additional, Ghosh, Tapasi, additional, Kanevsky, Boris, additional, Slysh, Vyacheslav, additional, Gunn, Alastair, additional, Burgess, Paul, additional, Carlson, Brent, additional, Del Rizzo, David, additional, Taylor, Russell, additional, Cannon, Wayne, additional, Kameno, Seiji, additional, Shibata, Kazunori M., additional, Benson, John, additional, Flatters, Chris, additional, Hale, Andrew, additional, Lewis, Craig, additional, Langston, Glen, additional, Minter, Anthony, additional, Miller, Kevin, additional, Smith, Joel, additional, Wietfeldt, Richard, additional, Altunin, Valery, additional, Meier, David L., additional, Murphy, David W., additional, Resch, George, additional, Lister, Matthew L., additional, Piner, B. Glenn, additional, Jenkins, Robert, additional, Border, James, additional, and Gimeno, Jesus, additional

Published
2000
Full Text
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