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1. Apertif 1.4 GHz continuum observations of the Bo\'otes field and their combined view with LOFAR

Author

Kutkin, A. M., Oosterloo, T. A., Morganti, R., Offringa, A. R., Adams, E. A. K., Adebahr, B., Dénes, H., Hess, K. M., van der Hulst, J. M., de Blok, W. J. G., Bozkurt, A., van Cappellen, W. A., Gunst, A. W., Holties, H. A., van Leeuwen, J., Loose, G. M., Oostrum, L. C., Vohl, D., Wijnholds, S. J., and Ziemke, J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We present a new image of a 26.5 square degree region in the Bo\"otes constellation obtained at 1.4 GHz using the Aperture Tile in Focus (Apertif) system on the Westerbork Synthesis Radio Telescope. We use a newly developed processing pipeline which includes direction-dependent self-calibration which provides a significant improvement of the quality of the images compared to those released as part of the Apertif first data release. For the Bo\"otes region, we mosaic 187 Apertif images and extract a source catalog. The mosaic image has an angular resolution of 27${\times}$11.5 arcseconds and a median background noise of 40 ${\mu}$Jy/beam. The catalog has 8994 sources and is complete down to the 0.3 mJy level. We combine the Apertif image with LOFAR images of the Bo\"otes field at 54 and 150 MHz to study spectral properties of the sources. We find a spectral flattening towards low flux density sources. Using the spectral index limits from Apertif non-detections we derive that up to 9 percent of the sources have ultra-steep spectra with a slope steeper than -1.2. Steepening of the spectral index with increasing redshift is also seen in the data showing a different dependency for the low-frequency spectral index and the high frequency one. This can be explained by a population of sources having concave radio spectra with a turnover frequency around the LOFAR band. Additionally, we discuss cases of individual extended sources with an interesting resolved spectral structure. With the improved pipeline, we aim to continue processing data from the Apertif wide-area surveys and release the improved 1.4 GHz images of several famous fields., Comment: 13 pages, 9 figures; to be published in A&A

Published
2023
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2. First release of Apertif imaging survey data

Author

Adams, Elizabeth A. K., Adebahr, B., de Blok, W. J. G., Denes, H., Hess, K. M., van der Hulst, J. M., Kutkin, A., Lucero, D. M., Morganti, R., Moss, V. A., Oosterloo, T. A., Orru, E., Schulz, R., van Amesfoort, A. S., Berger, A., Boersma, O. M., Bouwhuis, M., Brink, R. van den, van Cappellen, W. A., Connor, L., Coolen, A. H. W. M., Damstra, S., van Diepen, G. N. J., Dijkema, T. J., Ebbendorf, N., Grange, Y. G., de Goei, R., Gunst, A. W., Holties, H. A., Hut, B., Ivashina, M. V., Jozsa, G. I. G., Loose, G. M., van Leeuwen, J., Maan, Y., Mancini, M., Mika, A., Mulder, H., Norden, M. J., Offringa, A. R., Oostrum, L. C., Pastor-Marazuela, I., Pisano, D. J., Ponomareva, A. A., Romein, J. W., Ruiter, M, Schoenmakers, A. P., van der Schuur, D., Sluman, J. J., Smits, R., Stuurwold, K. J. C, Verstappen, J., Vilchez, N. P. E, Vohl, D., Wierenga, K. J., Wijnholds, S. J., Woestenburg, E. E. M., Zanting, A. W., and Ziemke, J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

(Abridged) Apertif is a phased-array feed system for WSRT, providing forty instantaneous beams over 300 MHz of bandwidth. A dedicated survey program started on 1 July 2019, with the last observations taken on 28 February 2022. We describe the release of data products from the first year of survey operations, through 30 June 2020. We focus on defining quality control metrics for the processed data products. The Apertif imaging pipeline, Apercal, automatically produces non-primary beam corrected continuum images, polarization images and cubes, and uncleaned spectral line and dirty beam cubes for each beam of an Apertif imaging observation. For this release, processed data products are considered on a beam-by-beam basis within an observation. We validate the continuum images by using metrics that identify deviations from Gaussian noise in the residual images. If the continuum image passes validation, we release all processed data products for a given beam. We apply further validation to the polarization and line data products. We release all raw observational data from the first year of survey observations, for a total of 221 observations of 160 independent target fields, covering approximately one thousand square degrees of sky. Images and cubes are released on a per beam basis, and 3374 beams are released. The median noise in the continuum images is 41.4 uJy/bm, with a slightly lower median noise of 36.9 uJy/bm in the Stokes V polarization image. The median angular resolution is 11.6"/sin(Dec). The median noise for all line cubes, with a spectral resolution of 36.6 kHz, is 1.6 mJy/bm, corresponding to a 3-sigma HI column density sensitivity of 1.8 x 10^20 atoms cm^-2 over 20 km/s (for a median angular resolution of 24" x 15"). We also provide primary beam images for each individual Apertif compound beam. The data are made accessible using a Virtual Observatory interface., Comment: Accepted for publication in A&A, updated Figure 1

Published
2022
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3. Apertif, Phased Array Feeds for the Westerbork Synthesis Radio Telescope

Author

van Cappellen, W. A., Oosterloo, T. A., Verheijen, M. A. W., Adams, E. A. K., Adebahr, B., Braun, R., Hess, K. M., Holties, H., van der Hulst, J. M., Hut, B., Kooistra, E., van Leeuwen, J., Loose, G. M., Morganti, R., Moss, V. A., Orrú, E., Ruiter, M., Schoenmakers, A. P., Vermaas, N. J., Wijnholds, S. J., van Amesfoort, A. S., Arts, M. J., Attema, J. J., Bakker, L., Bassa, C. G., Bast, J. E., Benthem, P., Beukema, R., Blaauw, R., de Blok, W. J. G., Bouwhuis, M., Brink, R. H. van den, Connor, L., Coolen, A. H. W. M., Damstra, S., van Diepen, G. N. J., de Goei, R., Dénes, H., Drost, M., Ebbendorf, N., Frank, B. S., Gardenier, D. W., Gerbers, M., Grange, Y. G., Grit, T., Gunst, A. W., Gupta, N., Ivashina, M. V., Józsa, G. I. G., Janssen, G. H., Koster, A., Kruithof, G. H., Kuindersma, S. J., Kutkin, A., Lucero, D. M., Maan, Y., Maccagni, F. M., van der Marel, J., Mika, A., Morawietz, J., Mulder, H., Mulder, E., Norden, M. J., Offringa, A. R., Oostrum, L. C., Overeem, R. E., Paragi, Z., Pepping, H. J., Petroff, E., Pisano, D. J., Polatidis, A. G., Prasad, P., de Reijer, J. P. R., Romein, J. W., Schaap, J., Schoonderbeek, G. W., Schulz, R., van der Schuur, D., Sclocco, A., Sluman, J. J., Smits, R., Stappers, B. W., Straal, S. M., Stuurwold, K. J. C., Verstappen, J., Vohl, D., Wierenga, K. J., Woestenburg, E. E. M., Zanting, A. W., and Ziemke, J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We describe the APERture Tile In Focus (Apertif) system, a phased array feed (PAF) upgrade of the Westerbork Synthesis Radio Telescope which has transformed this telescope into a high-sensitivity, wide field-of-view L-band imaging and transient survey instrument. Using novel PAF technology, up to 40 partially overlapping beams can be formed on the sky simultaneously, significantly increasing the survey speed of the telescope. With this upgraded instrument, an imaging survey covering an area of 2300 deg2 is being performed which will deliver both continuum and spectral line data sets, of which the first data has been publicly released. In addition, a time domain transient and pulsar survey covering 15,000 deg2 is in progress. An overview of the Apertif science drivers, hardware and software of the upgraded telescope is presented, along with its key performance characteristics., Comment: 29 pages, 42 figures, accepted for publication by A&A

Published
2021
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4. Target and (Astro-)WISE technologies - Data federations and its applications

Author

Valentijn, E. A., Begeman, K., Belikov, A., Boxhoorn, D. R., Brinchmann, J., McFarland, J., Holties, H., Kuijken, K. H., Kleijn, G. Verdoes, Vriend, W-J., Williams, O. R., Roerdink, J. B. T. M., Schomaker, L. R. B., Swertz, M. A., Tsyganov, A., and van Dijk, G. J. W.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

After its first implementation in 2003 the Astro-WISE technology has been rolled out in several European countries and is used for the production of the KiDS survey data. In the multi-disciplinary Target initiative this technology, nicknamed WISE technology, has been further applied to a large number of projects. Here, we highlight the data handling of other astronomical applications, such as VLT-MUSE and LOFAR, together with some non-astronomical applications such as the medical projects Lifelines and GLIMPS, the MONK handwritten text recognition system, and business applications, by amongst others, the Target Holding. We describe some of the most important lessons learned and describe the application of the data-centric WISE type of approach to the Science Ground Segment of the Euclid satellite., Comment: 9 pages, 5 figures, Proceedngs IAU Symposium No 325 Astroinformatics 2017

Published
2016
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5. The LOFAR Multifrequency Snapshot Sky Survey (MSSS) I. Survey description and first results

Author

Heald, G. H., Pizzo, R. F., Orrú, E., Breton, R. P., Carbone, D., Ferrari, C., Hardcastle, M. J., Jurusik, W., Macario, G., Mulcahy, D., Rafferty, D., Asgekar, A., Brentjens, M., Fallows, R. A., Frieswijk, W., Toribio, M. C., Adebahr, B., Arts, M., Bell, M. R., Bonafede, A., Bray, J., Broderick, J., Cantwell, T., Carroll, P., Cendes, Y., Clarke, A. O., Croston, J., Daiboo, S., de Gasperin, F., Gregson, J., Harwood, J., Hassall, T., Heesen, V., Horneffer, A., van der Horst, A. J., Iacobelli, M., Jelić, V., Jones, D., Kant, D., Kokotanekov, G., Martin, P., McKean, J. P., Morabito, L. K., Nikiel-Wroczyński, B., Offringa, A., Pandey, V. N., Pandey-Pommier, M., Pietka, M., Pratley, L., Riseley, C., Rowlinson, A., Sabater, J., Scaife, A. M. M., Scheers, L. H. A., Sendlinger, K., Shulevski, A., Sipior, M., Sobey, C., Stewart, A. J., Stroe, A., Swinbank, J., Tasse, C., Trüstedt, J., Varenius, E., van Velzen, S., Vilchez, N., van Weeren, R. J., Wijnholds, S., Williams, W. L., de Bruyn, A. G., Nijboer, R., Wise, M., Alexov, A., Anderson, J., Avruch, I. M., Beck, R., Bell, M. E., van Bemmel, I., Bentum, M. J., Bernardi, G., Best, P., Breitling, F., Brouw, W. N., Brüggen, M., Butcher, H. R., Ciardi, B., Conway, J. E., de Geus, E., de Jong, A., de Vos, M., Deller, A., Dettmar, R. J., Duscha, S., Eislöffel, J., Engels, D., Falcke, H., Fender, R., Garrett, M. A., Grießmeier, J., Gunst, A. W., Hamaker, J. P., Hessels, J. W. T., Hoeft, M., Hörandel, J., Holties, H. A., Intema, H., Jackson, N. J., Jütte, E., Karastergiou, A., Klijn, W. F. A., Kondratiev, V. I., Koopmans, L. V. E., Kuniyoshi, M., Kuper, G., Law, C., van Leeuwen, J., Loose, M., Maat, P., Markoff, S., McFadden, R., McKay-Bukowski, D., Mevius, M., Miller-Jones, J. C. A., Morganti, R., Munk, H., Nelles, A., Noordam, J. E., Norden, M. J., Paas, H., Polatidis, A. G., Reich, W., Renting, A., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Stappers, B. W., Steinmetz, M., Tagger, M., Tang, Y., ter Veen, S., Thoudam, S., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R. A. M. J., Wucknitz, O., Yatawatta, S., and Zarka, P.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky LOFAR imaging survey. In this introductory paper, we first describe in detail the motivation and design of the survey. Compared to previous radio surveys, MSSS is exceptional due to its intrinsic multifrequency nature providing information about the spectral properties of the detected sources over more than two octaves (from 30 to 160 MHz). The broadband frequency coverage, together with the fast survey speed generated by LOFAR's multibeaming capabilities, make MSSS the first survey of the sort anticipated to be carried out with the forthcoming Square Kilometre Array (SKA). Two of the sixteen frequency bands included in the survey were chosen to exactly overlap the frequency coverage of large-area Very Large Array (VLA) and Giant Metrewave Radio Telescope (GMRT) surveys at 74 MHz and 151 MHz respectively. The survey performance is illustrated within the "MSSS Verification Field" (MVF), a region of 100 square degrees centered at J2000 (RA,Dec)=(15h,69deg). The MSSS results from the MVF are compared with previous radio survey catalogs. We assess the flux and astrometric uncertainties in the catalog, as well as the completeness and reliability considering our source finding strategy. We determine the 90% completeness levels within the MVF to be 100 mJy at 135 MHz with 108" resolution, and 550 mJy at 50 MHz with 166" resolution. Images and catalogs for the full survey, expected to contain 150,000-200,000 sources, will be released to a public web server. We outline the plans for the ongoing production of the final survey products, and the ultimate public release of images and source catalogs., Comment: 23 pages, 19 figures. Accepted for publication in Astronomy & Astrophysics. MSSS Verification Field images and catalog data may be downloaded from http://vo.astron.nl

Published
2015
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6. 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, A., Enriquez, J. E., Falcke, H., Hörandel, J. R., Nelles, A., Rachen, J. P., Rossetto, L., Scholten, O., ter Veen, S., Thoudam, S., Ebert, U., Koehn, C., Rutjes, C., Alexov, A., Anderson, J. M., Avruch, I. M., Bentum, M. J., Bernardi, G., Best, P., Bonafede, A., Breitling, F., Broderick, J. W., Brüggen, M., Butcher, H. R., Ciardi, B., de Geus, E., de Vos, M., Duscha, S., Eislöffel, J., Fallows, R. A., Frieswijk, W., Garrett, M. A., Grießmeier, J., Gunst, A. W., Heald, G., Hessels, J. W. T., Hoeft, M., Holties, H. A., Juette, E., Kondratiev, V. I., Kuniyoshi, M., Kuper, G., Mann, G., McFadden, R., McKay-Bukowski, D., McKean, J. P., Mevius, M., Moldon, J., Norden, M. J., Orru, E., Paas, H., Pandey-Pommier, M., Pizzo, R., Polatidis, A. G., Reich, W., Röttgering, H., Scaife, A. M. M., Schwarz, D. J., Serylak, M., Smirnov, O., Steinmetz, M., Swinbank, J., Tagger, M., Tasse, C., Toribio, M. C., van Weeren, R. J., Vermeulen, R., Vocks, C., Wise, M. W., Wucknitz, O., and Zarka, P.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
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., Comment: 6 pages, 3 figures, accepted for publication in Physical Review Letters

Published
2015
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7. Detecting cosmic rays with the LOFAR radio telescope

Author

Schellart, P., Nelles, A., Buitink, S., Corstanje, A., Enriquez, J. E., Falcke, H., Frieswijk, W., Hörandel, J. R., Horneffer, A., James, C. W., Krause, M., Mevius, M., Scholten, O., ter Veen, S., Thoudam, S., Akker, M. van den, Alexov, A., Anderson, J., Avruch, I. M., Bähren, L., Beck, R., Bell, M. E., Bennema, P., Bentum, M. J., Bernardi, G., Best, P., Bregman, J., Breitling, F., Brentjens, M., Broderick, J., Brüggen, M., Ciardi, B., Coolen, A., de Gasperin, F., de Geus, E., de Jong, A., de Vos, M., Duscha, S., Eislöffel, J., Fallows, R. A., Ferrari, C., Garrett, M. A., Grießmeier, J., Grit, T., Hamaker, J. P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Holties, H. A., Iacobelli, M., Juette, E., Karastergiou, A., Klijn, W., Kohler, J., Kondratiev, V. I., Kramer, M., Kuniyoshi, M., Kuper, G., Maat, P., Macario, G., Mann, G., Markoff, S., McKay-Bukowski, D., McKean, J. P., Miller-Jones, J. C. A., Mol, J. D., Mulcahy, D. D., Munk, H., Nijboer, R., Norden, M. J., Orru, E., Overeem, R., Paas, H., Pandey-Pommier, M., Pizzo, R., Polatidis, A. G., Renting, A., Romein, J. W., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Sobey, C., Stappers, B. W., Steinmetz, M., Swinbank, J., Tang, Y., Tasse, C., Toribio, C., van Leeuwen, J., van Nieuwpoort, R., van Weeren, R. J., Vermaas, N., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R. A. M. J., Wijnholds, S. J., Wise, M. W., Wucknitz, O., Yatawatta, S., Zarka, P., and Zensus, A.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The low frequency array (LOFAR), is the first radio telescope designed with the capability to measure radio emission from cosmic-ray induced air showers in parallel with interferometric observations. In the first $\sim 2\,\mathrm{years}$ of observing, 405 cosmic-ray events in the energy range of $10^{16} - 10^{18}\,\mathrm{eV}$ have been detected in the band from $30 - 80\,\mathrm{MHz}$. Each of these air showers is registered with up to $\sim1000$ independent antennas resulting in measurements of the radio emission with unprecedented detail. This article describes the dataset, as well as the analysis pipeline, and serves as a reference for future papers based on these data. All steps necessary to achieve a full reconstruction of the electric field at every antenna position are explained, including removal of radio frequency interference, correcting for the antenna response and identification of the pulsed signal.

Published
2013
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8. LOFAR: The LOw-Frequency ARray

Author

van Haarlem, M. P., Wise, M. W., Gunst, A. W., Heald, G., McKean, J. P., Hessels, J. W. T., de Bruyn, A. G., Nijboer, R., Swinbank, J., Fallows, R., Brentjens, M., Nelles, A., Beck, R., Falcke, H., Fender, R., Hörandel, J., Koopmans, L. V. E., Mann, G., Miley, G., Röttgering, H., Stappers, B. W., Wijers, R. A. M. J., Zaroubi, S., Akker, M. van den, Alexov, A., Anderson, J., Anderson, K., van Ardenne, A., Arts, M., Asgekar, A., Avruch, I. M., Batejat, F., Bähren, L., Bell, M. E., Bell, M. R., van Bemmel, I., Bennema, P., Bentum, M. J., Bernardi, G., Best, P., Bîrzan, L., Bonafede, A., Boonstra, A. -J., Braun, R., Bregman, J., Breitling, F., van de Brink, R. H., Broderick, J., Broekema, P. C., Brouw, W. N., Brüggen, M., Butcher, H. R., van Cappellen, W., Ciardi, B., Coenen, T., Conway, J., Coolen, A., Corstanje, A., Damstra, S., Davies, O., Deller, A. T., Dettmar, R. -J., van Diepen, G., Dijkstra, K., Donker, P., Doorduin, A., Dromer, J., Drost, M., van Duin, A., Eislöffel, J., van Enst, J., Ferrari, C., Frieswijk, W., Gankema, H., Garrett, M. A., de Gasperin, F., Gerbers, M., de Geus, E., Grießmeier, J. -M., Grit, T., Gruppen, P., Hamaker, J. P., Hassall, T., Hoeft, M., Holties, H., Horneffer, A., van der Horst, A., van Houwelingen, A., Huijgen, A., Iacobelli, M., Intema, H., Jackson, N., Jelic, V., de Jong, A., Juette, E., Kant, D., Karastergiou, A., Koers, A., Kollen, H., Kondratiev, V. I., Kooistra, E., Koopman, Y., Koster, A., Kuniyoshi, M., Kramer, M., Kuper, G., Lambropoulos, P., Law, C., van Leeuwen, J., Lemaitre, J., Loose, M., Maat, P., Macario, G., Markoff, S., Masters, J., McKay-Bukowski, D., Meijering, H., Meulman, H., Mevius, M., Middelberg, E., Millenaar, R., Miller-Jones, J. C. A., Mohan, R. N., Mol, J. D., Morawietz, J., Morganti, R., Mulcahy, D. D., Mulder, E., Munk, H., Nieuwenhuis, L., van Nieuwpoort, R., Noordam, J. E., Norden, M., Noutsos, A., Offringa, A. R., Olofsson, H., Omar, A., Orrú, E., Overeem, R., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pizzo, R., Polatidis, A., Rafferty, D., Rawlings, S., Reich, W., de Reijer, J. -P., Reitsma, J., Renting, A., Riemers, P., Rol, E., Romein, J. W., Roosjen, J., Ruiter, M., Scaife, A., van der Schaaf, K., Scheers, B., Schellart, P., Schoenmakers, A., Schoonderbeek, G., Serylak, M., Shulevski, A., Sluman, J., Smirnov, O., Sobey, C., Spreeuw, H., Steinmetz, M., Sterks, C. G. M., Stiepel, H. -J., Stuurwold, K., Tagger, M., Tang, Y., Tasse, C., Thomas, I., Thoudam, S., Toribio, M. C., van der Tol, B., Usov, O., van Veelen, M., van der Veen, A. -J., ter Veen, S., Verbiest, J. P. W., Vermeulen, R., Vermaas, N., Vocks, C., Vogt, C., de Vos, M., van der Wal, E., van Weeren, R., Weggemans, H., Weltevrede, P., White, S., Wijnholds, S. J., Wilhelmsson, T., Wucknitz, O., Yatawatta, S., Zarka, P., Zensus, A., and van Zwieten, J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10-240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of Exloo in the northeast of the Netherlands, a total of 40 LOFAR stations are nearing completion. A further five stations have been deployed throughout Germany, and one station has been built in each of France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unparalleled sensitivity and angular resolution in the low-frequency radio regime. The LOFAR facilities are jointly operated by the International LOFAR Telescope (ILT) foundation, as an observatory open to the global astronomical community. LOFAR is one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. LOFAR's new capabilities, techniques and modus operandi make it an important pathfinder for the Square Kilometre Array (SKA). We give an overview of the LOFAR instrument, its major hardware and software components, and the core science objectives that have driven its design. In addition, we present a selection of new results from the commissioning phase of this new radio observatory., Comment: 56 pages, 34 figures, accepted for publication by A&A

Published
2013
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9. Wide-band Simultaneous Observations of Pulsars: Disentangling Dispersion Measure and Profile Variations

Author

Hassall, T. E., Stappers, B. W., Hessels, J. W. T., Kramer, M., Alexov, A., Anderson, K., Coenen, T., Karastergiou, A., Keane, E. F., Kondratiev, V. I., Lazaridis, K., van Leeuwen, J., Noutsos, A., Serylak, M., Sobey, C., Verbiest, J. P. W., Weltevrede, P., Zagkouris, K., Fender, R., Wijers, R. A. M. J., Bahren, L., Bell, M. E., Broderick, J. W., Corbel, S., Daw, E. J., Dhillon, V. S., Eisloffel, J., Falcke, H., Griessmeier, J. -M., Jonker, P., Law, C., Markoff, S., Miller-Jones, J. C. A., Osten, R., Rol, E., Scaife, A. M. M., Scheers, B., Schellart, P., Spreeuw, H., Swinbank, J., ter Veen, S., Wise, M. W., Wijnands, R., Wucknitz, O., Zarka, P., Asgekar, A., Bell, M. R., Bentum, M. J., Bernardi, G., Best, P., Bonafede, A., Boonstra, A. J., Brentjens, M., Brouw, W. N., Bruggen, M., Butcher, H. R., Ciardi, B., Garrett, M. A., Gerbers, M., Gunst, A. W., van Haarlem, M. P., Heald, G., Hoeft, M., Holties, H., de Jong, A., Koopmans, L. V. E., Kuniyoshi, M., Kuper, G., Loose, G. M., Maat, P., Masters, J., McKean, J. P., Meulman, H., Mevius, M., Munk, H., Noordam, J. E., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pizzo, R., Polatidis, A., Reich, W., Rottgering, H., Sluman, J., Steinmetz, M., Sterks, C. G. M., Tagger, M., Tang, Y., Tasse, C., Vermeulen, R., van Weeren, R. J., Wijnholds, S. J., and Yatawatta, S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Dispersion in the interstellar medium is a well known phenomenon that follows a simple relationship, which has been used to predict the time delay of dispersed radio pulses since the late 1960s. We performed wide-band simultaneous observations of four pulsars with LOFAR (at 40-190 MHz), the 76-m Lovell Telescope (at 1400 MHz) and the Effelsberg 100-m Telescope (at 8000 MHz) to test the accuracy of the dispersion law over a broad frequency range. In this paper we present the results of these observations which show that the dispersion law is accurate to better than 1 part in 100000 across our observing band. We use this fact to constrain some of the properties of the ISM along the line-of-sight and use the lack of any aberration or retardation effects to determine upper limits on emission heights in the pulsar magnetosphere. We also discuss the effect of pulse profile evolution on our observations, and the implications that it could have for precision pulsar timing projects such as the detection of gravitational waves with pulsar timing arrays., Comment: 20 Pages, 14 Figures, Accepted for publication in Astronomy & Astrophysics

Published
2012
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10. Optimized Trigger for Ultra-High-Energy Cosmic-Ray and Neutrino Observations with the Low Frequency Radio Array

Author

Singh, K., Mevius, M., Scholten, O., Anderson, J. M., van Ardenne, A., Arts, M., Avruch, M., Asgekar, A., Bell, M., Bennema, P., Bentum, M., Bernadi, G., Best, P., Boonstra, A. -J., Bregman, J., van de Brink, R., Broekema, C., Brouw, W., Brueggen, M., Buitink, S., Butcher, H., van Cappellen, W., Ciardi, B., Coolen, A., Damstra, S., Dettmar, R., van Diepen, G., Dijkstra, K., Donker, P., Doorduin, A., Drost, M., van Duin, A., Eisloeffel, J., Falcke, H., Garrett, M., Gerbers, M., Griessmeier, J., Grit, T., Gruppen, P., Gunst, A., van Haarlem, M., Hoeft, M., Holties, H., Horandel, J., Horneffer, L. A., Huijgen, A., James, C., de Jong, A., Kant, D., Kooistra, E., Koopman, Y., Koopmans, L., Kuper, G., Lambropoulos, P., van Leeuwen, J., Loose, M., Maat, P., Mallary, C., McFadden, R., Meulman, H., Mol, J. -D., Morawietz, J., Mulder, E., Munk, H., Nieuwenhuis, L., Nijboer, R., Norden, M., Noordam, J., Overeem, R., Paas, H., Pandey, V. N., Pandey-Pommier, M., Pizzo, R., Polatidis, A., Reich, W., de Reijer, J., Renting, A., Riemers, P., Roettgering, H., Romein, J., Roosjen, J., Ruiter, M., Schoenmakers, A., Schoonderbeek, G., Sluman, J., Smirnov, O., Stappers, B., Steinmetz, M., Stiepel, H., Stuurwold, K., Tagger, M., Tang, Y., ter Veen, S., Vermeulen, R., de Vos, M., Vogt, C., van der Wal, E., Weggemans, H., Wijnholds, S., Wise, M., Wucknitz, O., Yattawatta, S., and van Zwieten, J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

When an ultra-high energy neutrino or cosmic ray strikes the Lunar surface a radio-frequency pulse is emitted. We plan to use the LOFAR radio telescope to detect these pulses. In this work we propose an efficient trigger implementation for LOFAR optimized for the observation of short radio pulses., Comment: Submitted to Nuclear Instruments and Methods in Physics Research Section A

Published
2011
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11. Observing pulsars and fast transients with LOFAR

Author

Stappers, B. W., Hessels, J. W. T., Alexov, A., Anderson, K., Coenen, T., Hassall, T., Karastergiou, A., Kondratiev, V. I., Kramer, M., van Leeuwen, J., Mol, J. D., Noutsos, A., Romein, J. W ., Weltevrede, P., Fender, R., Wijers, R. A. M. J., Bähren, L., Bell, M. E., Broderick, J., Daw, E. J., Dhillon, V. S., Eislöffel, J., Falcke, H., Griessmeier, J., Law, C., Markoff, S., Miller-Jones, J. C. A., Scheers, B., Spreeuw, H., Swinbank, J., ter Veen, S., Wise, M. W., Wucknitz, O., Zarka, P., Anderson, J., Asgekar, A., Avruch, I. M., Beck, R., Bennema, P., Bentum, M. J., Best, P., Bregman, J., Brentjens, M., van de Brink, R. H., Broekema, P. C., Brouw, W. N., Brüggen, M., de Bruyn, A. G., Butcher, H. R., Ciardi, B., Conway, J., Dettmar, R. -J., van Duin, A., van Enst, J., Garrett, M., Gerbers, M., Grit, T., Gunst, A., van Haarlem, M. P., Hamaker, J. P., Heald, G., Hoeft, M., Holties, H., Horneffer, A., Koopmans, L. V. E., Kuper, G., Loose, M., Maat, P., McKay-Bukowski, D., McKean, J. P., Miley, G., Morganti, R., Nijboer, R., Noordam, J. E., Norden, M., Olofsson, H., Pandey-Pommier, M., Polatidis, A., Reich, W., Röttgering, H., Schoenmakers, A., Sluman, J., Smirnov, O., Steinmetz, M., Sterks, C. G. M., Tagger, M., Tang, Y., Vermeulen, R., Vermaas, N., Vogt, C., de Vos, M., Wijnholds, S. J., Yatawatta, S., and Zensus, A.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

Low frequency radio waves, while challenging to observe, are a rich source of information about pulsars. The LOw Frequency ARray (LOFAR) is a new radio interferometer operating in the lowest 4 octaves of the ionospheric "radio window": 10-240MHz, that will greatly facilitate observing pulsars at low radio frequencies. Through the huge collecting area, long baselines, and flexible digital hardware, it is expected that LOFAR will revolutionize radio astronomy at the lowest frequencies visible from Earth. LOFAR is a next-generation radio telescope and a pathfinder to the Square Kilometre Array (SKA), in that it incorporates advanced multi-beaming techniques between thousands of individual elements. We discuss the motivation for low-frequency pulsar observations in general and the potential of LOFAR in addressing these science goals. We present LOFAR as it is designed to perform high-time-resolution observations of pulsars and other fast transients, and outline the various relevant observing modes and data reduction pipelines that are already or will soon be implemented to facilitate these observations. A number of results obtained from commissioning observations are presented to demonstrate the exciting potential of the telescope. This paper outlines the case for low frequency pulsar observations and is also intended to serve as a reference for upcoming pulsar/fast transient science papers with LOFAR., Comment: 35 pages, 19 figures, accepted for publication by A&A

Published
2011
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12. Apertif 1.4 GHz continuum observations of the Boötes field and their combined view with LOFAR

Author

Kutkin, A. M., primary, Oosterloo, T. A., additional, Morganti, R., additional, Offringa, A. R., additional, Adams, E. A. K., additional, Adebahr, B., additional, Dénes, H., additional, Hess, K. M., additional, van der Hulst, J. M., additional, de Blok, W. J. G., additional, Bozkurt, A., additional, van Cappellen, W. A., additional, Gunst, A. W., additional, Holties, H. A., additional, van Leeuwen, J., additional, Loose, G. M., additional, Oostrum, L. C., additional, Vohl, D., additional, Wijnholds, S. J., additional, and Ziemke, J., additional

Published
2023
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13. First release of Apertif imaging survey data

Author

Adams, E. A. K., primary, Adebahr, B., additional, de Blok, W. J. G., additional, Dénes, H., additional, Hess, K. M., additional, van der Hulst, J. M., additional, Kutkin, A., additional, Lucero, D. M., additional, Morganti, R., additional, Moss, V. A., additional, Oosterloo, T. A., additional, Orrú, E., additional, Schulz, R., additional, van Amesfoort, A. S., additional, Berger, A., additional, Boersma, O. M., additional, Bouwhuis, M., additional, van den Brink, R., additional, van Cappellen, W. A., additional, Connor, L., additional, Coolen, A. H. W. M., additional, Damstra, S., additional, van Diepen, G. N. J., additional, Dijkema, T. J., additional, Ebbendorf, N., additional, Grange, Y. G., additional, de Goei, R., additional, Gunst, A. W., additional, Holties, H. A., additional, Hut, B., additional, Ivashina, M. V., additional, Józsa, G. I. G., additional, van Leeuwen, J., additional, Loose, G. M., additional, Maan, Y., additional, Mancini, M., additional, Mika, Á., additional, Mulder, H., additional, Norden, M. J., additional, Offringa, A. R., additional, Oostrum, L. C., additional, Pastor-Marazuela, I., additional, Pisano, D. J., additional, Ponomareva, A. A., additional, Romein, J. W., additional, Ruiter, M., additional, Schoenmakers, A. P., additional, van der Schuur, D., additional, Sluman, J. J., additional, Smits, R., additional, Stuurwold, K. J. C., additional, Verstappen, J., additional, Vilchez, N. P. E., additional, Vohl, D., additional, Wierenga, K. J., additional, Wijnholds, S. J., additional, Woestenburg, E. E. M., additional, Zanting, A. W., additional, and Ziemke, J., additional

Published
2022
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14. Apertif: Phased array feeds for the Westerbork Synthesis Radio Telescope

Author

van Cappellen, W. A., primary, Oosterloo, T. A., additional, Verheijen, M. A. W., additional, Adams, E. A. K., additional, Adebahr, B., additional, Braun, R., additional, Hess, K. M., additional, Holties, H., additional, van der Hulst, J. M., additional, Hut, B., additional, Kooistra, E., additional, van Leeuwen, J., additional, Loose, G. M., additional, Morganti, R., additional, Moss, V. A., additional, Orrú, E., additional, Ruiter, M., additional, Schoenmakers, A. P., additional, Vermaas, N. J., additional, Wijnholds, S. J., additional, van Amesfoort, A. S., additional, Arts, M. J., additional, Attema, J. J., additional, Bakker, L., additional, Bassa, C. G., additional, Bast, J. E., additional, Benthem, P., additional, Beukema, R., additional, Blaauw, R., additional, de Blok, W. J. G., additional, Bouwhuis, M., additional, van den Brink, R. H., additional, Connor, L., additional, Coolen, A. H. W. M., additional, Damstra, S., additional, van Diepen, G. N. J., additional, de Goei, R., additional, Dénes, H., additional, Drost, M., additional, Ebbendorf, N., additional, Frank, B. S., additional, Gardenier, D. W., additional, Gerbers, M., additional, Grange, Y. G., additional, Grit, T., additional, Gunst, A. W., additional, Gupta, N., additional, Ivashina, M. V., additional, Józsa, G. I. G., additional, Janssen, G. H., additional, Koster, A., additional, Kruithof, G. H., additional, Kuindersma, S. J., additional, Kutkin, A., additional, Lucero, D. M., additional, Maan, Y., additional, Maccagni, F. M., additional, van der Marel, J., additional, Mika, A., additional, Morawietz, J., additional, Mulder, H., additional, Mulder, E., additional, Norden, M. J., additional, Offringa, A. R., additional, Oostrum, L. C., additional, Overeem, R. E., additional, Paragi, Z., additional, Pepping, H. J., additional, Petroff, E., additional, Pisano, D. J., additional, Polatidis, A. G., additional, Prasad, P., additional, de Reijer, J. P. R., additional, Romein, J. W., additional, Schaap, J., additional, Schoonderbeek, G. W., additional, Schulz, R., additional, van der Schuur, D., additional, Sclocco, A., additional, Sluman, J. J., additional, Smits, R., additional, Stappers, B. W., additional, Straal, S. M., additional, Stuurwold, K. J. C., additional, Verstappen, J., additional, Vohl, D., additional, Wierenga, K. J., additional, Woestenburg, E. E. M., additional, Zanting, A. W., additional, and Ziemke, J., additional

Published
2022
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15. LOFAR Information System

Author

Begeman, K., Belikov, A.N., Boxhoorn, D.R., Dijkstra, F., Holties, H., Meyer-Zhao, Z., Renting, G.A., Valentijn, E.A., and Vriend, W.-J.

Published
2011
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16. Apertif: lessons learned operating a Phased Array Feed array

Author

Orru, E., primary, Adams, E. A. K., additional, Bouwhuis, M., additional, Coolen, A., additional, Holties, H., additional, van Leeuwen, J., additional, Moss, V. A., additional, Mulder, H., additional, Norden, M., additional, Oostrum, L. C., additional, Schoenmakers, A., additional, van der Tol, S., additional, and Veermas, N., additional

Published
2021
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18. Low-frequency radio absorption in Cassiopeia A

Author

Arias, M., primary, Vink, J., additional, de Gasperin, F., additional, Salas, P., additional, Oonk, J. B. R., additional, van Weeren, R. J., additional, van Amesfoort, A. S., additional, Anderson, J., additional, Beck, R., additional, Bell, M. E., additional, Bentum, M. J., additional, Best, P., additional, Blaauw, R., additional, Breitling, F., additional, Broderick, J. W., additional, Brouw, W. N., additional, Brüggen, M., additional, Butcher, H. R., additional, Ciardi, B., additional, de Geus, E., additional, Deller, A., additional, van Dijk, P. C. G., additional, Duscha, S., additional, Eislöffel, J., additional, Garrett, M. A., additional, Grießmeier, J. M., additional, Gunst, A. W., additional, van Haarlem, M. P., additional, Heald, G., additional, Hessels, J., additional, Hörandel, J., additional, Holties, H. A., additional, van der Horst, A. J., additional, Iacobelli, M., additional, Juette, E., additional, Krankowski, A., additional, van Leeuwen, J., additional, Mann, G., additional, McKay-Bukowski, D., additional, McKean, J. P., additional, Mulder, H., additional, Nelles, A., additional, Orru, E., additional, Paas, H., additional, Pandey-Pommier, M., additional, Pandey, V. N., additional, Pekal, R., additional, Pizzo, R., additional, Polatidis, A. G., additional, Reich, W., additional, Röttgering, H. J. A., additional, Rothkaehl, H., additional, Schwarz, D. J., additional, Smirnov, O., additional, Soida, M., additional, Steinmetz, M., additional, Tagger, M., additional, Thoudam, S., additional, Toribio, M. C., additional, Vocks, C., additional, van der Wiel, M. H. D., additional, Wijers, R. A. M. J., additional, Wucknitz, O., additional, Zarka, P., additional, and Zucca, P., additional

Published
2018
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20. Target and (Astro-)WISE technologies Data federations and its applications

Author

Valentijn, E. A., primary, Begeman, K., additional, Belikov, A., additional, Boxhoorn, D. R., additional, Brinchmann, J., additional, McFarland, J., additional, Holties, H., additional, Kuijken, K. H., additional, Kleijn, G. Verdoes, additional, Vriend, W-J., additional, Williams, O. R., additional, Roerdink, J. B. T. M., additional, Schomaker, L. R. B., additional, Swertz, M. A., additional, Tsyganov, A., additional, and van Dijk, G. J. W., additional

Published
2016
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21. The LOFAR Multifrequency Snapshot Sky Survey (MSSS)

Author

Heald, G., Pizzo, R., Orrú, E., Breton, R., Carbone, D., Ferrari, C., Hardcastle, M., Jurusik, W., Macario, G., Mulcahy, D., Rafferty, D., Asgekar, A., Brentjens, M., Fallows, R., Frieswijk, W., Toribio, M., Adebahr, B., Arts, M., Bell, M., Bonafede, A., Bray, J., Broderick, J., Cantwell, T., Carroll, P., Cendes, Y., Clarke, A., Croston, J., Daiboo, S., de Gasperin, F., Gregson, J., Harwood, J., Hassall, T., Heesen, V., Horneffer, A., van der Horst, A., Iacobelli, M., Jelić, V., Jones, D., Kant, D., Kokotanekov, G., Martin, P., McKean, J., Morabito, L., Nikiel-Wroczyński, B., Offringa, A., Pandey, V., Pandey-Pommier, M., Pietka, M., Pratley, L., Riseley, C., Rowlinson, A., Sabater, J., Scaife, A., Scheers, L., Sendlinger, K., Shulevski, A., Sipior, M., Sobey, C., Stewart, A., Stroe, A., Swinbank, J., Tasse, C., Trüstedt, J., Varenius, E., van Velzen, S., Vilchez, N., van Weeren, R., Wijnholds, S., Williams, W., de Bruyn, A., Nijboer, R., Wise, M., Alexov, A., Anderson, J., Avruch, I., Beck, R., van Bemmel, I., Bentum, M., Bernardi, G., Best, P., Breitling, F., Brouw, W., Brüggen, M., Butcher, H., Ciardi, B., Conway, J., de Geus, E., de Jong, A., de Vos, M., Deller, A., Dettmar, R., Duscha, S., Eislöffel, J., Engels, D., Falcke, H., Fender, R., Garrett, M., Grießmeier, J., Gunst, A., Hamaker, J., Hessels, J., Hoeft, M., Hörandel, J., Holties, H., Intema, H., Jackson, N., Jütte, E., Karastergiou, A., Klijn, W., Kondratiev, V., Koopmans, L., Kuniyoshi, M., Kuper, G., Law, C., van Leeuwen, J., Loose, M., Maat, P., Markoff, S., McFadden, R., McKay-Bukowski, D., Mevius, M., Miller-Jones, J., Morganti, R., Munk, H., Nelles, A., Noordam, J., Norden, M., Paas, H., Polatidis, A., Reich, W., Renting, A., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Stappers, B., Steinmetz, M., Tagger, M., Tang, Y., ter Veen, S., Thoudam, S., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R., Wucknitz, O., Yatawatta, S., and Zarka, P.

Abstract

We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky Low Frequency Array (LOFAR) imaging survey. In this introductory paper, we first describe in detail the motivation and design of the survey. Compared to previous radio surveys, MSSS is exceptional due to its intrinsic multifrequency nature providing information about the spectral properties of the detected sources over more than two octaves (from 30 to 160 MHz). The broadband frequency coverage, together with the fast survey speed generated by LOFAR’s multibeaming capabilities, make MSSS the first survey of the sort anticipated to be carried out with the forthcoming Square Kilometre Array (SKA). Two of the sixteen frequency bands included in the survey were chosen to exactly overlap the frequency coverage of large-area Very Large Array (VLA) and Giant Metrewave Radio Telescope (GMRT) surveys at 74 MHz and 151 MHz respectively. The survey performance is illustrated within the MSSS Verification Field (MVF), a region of 100 square degrees centered at (α,δ)J2000 = (15h,69°). The MSSS results from the MVF are compared with previous radio survey catalogs. We assess the flux and astrometric uncertainties in the catalog, as well as the completeness and reliability considering our source finding strategy. We determine the 90% completeness levels within the MVF to be 100 mJy at 135 MHz with 108" resolution, and 550 mJy at 50 MHz with 166" resolution. Images and catalogs for the full survey, expected to contain 150,000–200,000 sources, will be released to a public web server. We outline the plans for the ongoing production of the final survey products, and the ultimate public release of images and source catalogs.

Published
2015

22. The LOFAR Multifrequency Snapshot Sky Survey (MSSS)

Author

Heald, G. H., primary, Pizzo, R. F., additional, Orrú, E., additional, Breton, R. P., additional, Carbone, D., additional, Ferrari, C., additional, Hardcastle, M. J., additional, Jurusik, W., additional, Macario, G., additional, Mulcahy, D., additional, Rafferty, D., additional, Asgekar, A., additional, Brentjens, M., additional, Fallows, R. A., additional, Frieswijk, W., additional, Toribio, M. C., additional, Adebahr, B., additional, Arts, M., additional, Bell, M. R., additional, Bonafede, A., additional, Bray, J., additional, Broderick, J., additional, Cantwell, T., additional, Carroll, P., additional, Cendes, Y., additional, Clarke, A. O., additional, Croston, J., additional, Daiboo, S., additional, de Gasperin, F., additional, Gregson, J., additional, Harwood, J., additional, Hassall, T., additional, Heesen, V., additional, Horneffer, A., additional, van der Horst, A. J., additional, Iacobelli, M., additional, Jelić, V., additional, Jones, D., additional, Kant, D., additional, Kokotanekov, G., additional, Martin, P., additional, McKean, J. P., additional, Morabito, L. K., additional, Nikiel-Wroczyński, B., additional, Offringa, A., additional, Pandey, V. N., additional, Pandey-Pommier, M., additional, Pietka, M., additional, Pratley, L., additional, Riseley, C., additional, Rowlinson, A., additional, Sabater, J., additional, Scaife, A. M. M., additional, Scheers, L. H. A., additional, Sendlinger, K., additional, Shulevski, A., additional, Sipior, M., additional, Sobey, C., additional, Stewart, A. J., additional, Stroe, A., additional, Swinbank, J., additional, Tasse, C., additional, Trüstedt, J., additional, Varenius, E., additional, van Velzen, S., additional, Vilchez, N., additional, van Weeren, R. J., additional, Wijnholds, S., additional, Williams, W. L., additional, de Bruyn, A. G., additional, Nijboer, R., additional, Wise, M., additional, Alexov, A., additional, Anderson, J., additional, Avruch, I. M., additional, Beck, R., additional, Bell, M. E., additional, van Bemmel, I., additional, Bentum, M. J., additional, Bernardi, G., additional, Best, P., additional, Breitling, F., additional, Brouw, W. N., additional, Brüggen, M., additional, Butcher, H. R., additional, Ciardi, B., additional, Conway, J. E., additional, de Geus, E., additional, de Jong, A., additional, de Vos, M., additional, Deller, A., additional, Dettmar, R.-J., additional, Duscha, S., additional, Eislöffel, J., additional, Engels, D., additional, Falcke, H., additional, Fender, R., additional, Garrett, M. A., additional, Grießmeier, J., additional, Gunst, A. W., additional, Hamaker, J. P., additional, Hessels, J. W. T., additional, Hoeft, M., additional, Hörandel, J., additional, Holties, H. A., additional, Intema, H., additional, Jackson, N. J., additional, Jütte, E., additional, Karastergiou, A., additional, Klijn, W. F. A., additional, Kondratiev, V. I., additional, Koopmans, L. V. E., additional, Kuniyoshi, M., additional, Kuper, G., additional, Law, C., additional, van Leeuwen, J., additional, Loose, M., additional, Maat, P., additional, Markoff, S., additional, McFadden, R., additional, McKay-Bukowski, D., additional, Mevius, M., additional, Miller-Jones, J. C. A., additional, Morganti, R., additional, Munk, H., additional, Nelles, A., additional, Noordam, J. E., additional, Norden, M. J., additional, Paas, H., additional, Polatidis, A. G., additional, Reich, W., additional, Renting, A., additional, Röttgering, H., additional, Schoenmakers, A., additional, Schwarz, D., additional, Sluman, J., additional, Smirnov, O., additional, Stappers, B. W., additional, Steinmetz, M., additional, Tagger, M., additional, Tang, Y., additional, ter Veen, S., additional, Thoudam, S., additional, Vermeulen, R., additional, Vocks, C., additional, Vogt, C., additional, Wijers, R. A. M. J., additional, Wucknitz, O., additional, Yatawatta, S., additional, and Zarka, P., additional

Published
2015
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23. Probing Atmospheric Electric Fields in Thunderstorms through Radio Emission from Cosmic-Ray-Induced Air Showers

Author

Schellart, P., primary, Trinh, T. N. G., additional, Buitink, S., additional, Corstanje, A., additional, Enriquez, J. E., additional, Falcke, H., additional, Hörandel, J. R., additional, Nelles, A., additional, Rachen, J. P., additional, Rossetto, L., additional, Scholten, O., additional, ter Veen, S., additional, Thoudam, S., additional, Ebert, U., additional, Koehn, C., additional, Rutjes, C., additional, Alexov, A., additional, Anderson, J. M., additional, Avruch, I. M., additional, Bentum, M. J., additional, Bernardi, G., additional, Best, P., additional, Bonafede, A., additional, Breitling, F., additional, Broderick, J. W., additional, Brüggen, M., additional, Butcher, H. R., additional, Ciardi, B., additional, de Geus, E., additional, de Vos, M., additional, Duscha, S., additional, Eislöffel, J., additional, Fallows, R. A., additional, Frieswijk, W., additional, Garrett, M. A., additional, Grießmeier, J., additional, Gunst, A. W., additional, Heald, G., additional, Hessels, J. W. T., additional, Hoeft, M., additional, Holties, H. A., additional, Juette, E., additional, Kondratiev, V. I., additional, Kuniyoshi, M., additional, Kuper, G., additional, Mann, G., additional, McFadden, R., additional, McKay-Bukowski, D., additional, McKean, J. P., additional, Mevius, M., additional, Moldon, J., additional, Norden, M. J., additional, Orru, E., additional, Paas, H., additional, Pandey-Pommier, M., additional, Pizzo, R., additional, Polatidis, A. G., additional, Reich, W., additional, Röttgering, H., additional, Scaife, A. M. M., additional, Schwarz, D. J., additional, Serylak, M., additional, Smirnov, O., additional, Steinmetz, M., additional, Swinbank, J., additional, Tagger, M., additional, Tasse, C., additional, Toribio, M. C., additional, van Weeren, R. J., additional, Vermeulen, R., additional, Vocks, C., additional, Wise, M. W., additional, Wucknitz, O., additional, and Zarka, P., additional

Published
2015
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24. Detecting cosmic rays with the LOFAR radio telescope

Author

Schellart, P., primary, Nelles, A., additional, Buitink, S., additional, Corstanje, A., additional, Enriquez, J. E., additional, Falcke, H., additional, Frieswijk, W., additional, Hörandel, J. R., additional, Horneffer, A., additional, James, C. W., additional, Krause, M., additional, Mevius, M., additional, Scholten, O., additional, ter Veen, S., additional, Thoudam, S., additional, van den Akker, M., additional, Alexov, A., additional, Anderson, J., additional, Avruch, I. M., additional, Bähren, L., additional, Beck, R., additional, Bell, M. E., additional, Bennema, P., additional, Bentum, M. J., additional, Bernardi, G., additional, Best, P., additional, Bregman, J., additional, Breitling, F., additional, Brentjens, M., additional, Broderick, J., additional, Brüggen, M., additional, Ciardi, B., additional, Coolen, A., additional, de Gasperin, F., additional, de Geus, E., additional, de Jong, A., additional, de Vos, M., additional, Duscha, S., additional, Eislöffel, J., additional, Fallows, R. A., additional, Ferrari, C., additional, Garrett, M. A., additional, Grießmeier, J., additional, Grit, T., additional, Hamaker, J. P., additional, Hassall, T. E., additional, Heald, G., additional, Hessels, J. W. T., additional, Hoeft, M., additional, Holties, H. A., additional, Iacobelli, M., additional, Juette, E., additional, Karastergiou, A., additional, Klijn, W., additional, Kohler, J., additional, Kondratiev, V. I., additional, Kramer, M., additional, Kuniyoshi, M., additional, Kuper, G., additional, Maat, P., additional, Macario, G., additional, Mann, G., additional, Markoff, S., additional, McKay-Bukowski, D., additional, McKean, J. P., additional, Miller-Jones, J. C. A., additional, Mol, J. D., additional, Mulcahy, D. D., additional, Munk, H., additional, Nijboer, R., additional, Norden, M. J., additional, Orru, E., additional, Overeem, R., additional, Paas, H., additional, Pandey-Pommier, M., additional, Pizzo, R., additional, Polatidis, A. G., additional, Renting, A., additional, Romein, J. W., additional, Röttgering, H., additional, Schoenmakers, A., additional, Schwarz, D., additional, Sluman, J., additional, Smirnov, O., additional, Sobey, C., additional, Stappers, B. W., additional, Steinmetz, M., additional, Swinbank, J., additional, Tang, Y., additional, Tasse, C., additional, Toribio, C., additional, van Leeuwen, J., additional, van Nieuwpoort, R., additional, van Weeren, R. J., additional, Vermaas, N., additional, Vermeulen, R., additional, Vocks, C., additional, Vogt, C., additional, Wijers, R. A. M. J., additional, Wijnholds, S. J., additional, Wise, M. W., additional, Wucknitz, O., additional, Yatawatta, S., additional, Zarka, P., additional, and Zensus, A., additional

Published
2013
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25. LOFAR: The LOw-Frequency ARray

Author

van Haarlem, M. P., primary, Wise, M. W., additional, Gunst, A. W., additional, Heald, G., additional, McKean, J. P., additional, Hessels, J. W. T., additional, de Bruyn, A. G., additional, Nijboer, R., additional, Swinbank, J., additional, Fallows, R., additional, Brentjens, M., additional, Nelles, A., additional, Beck, R., additional, Falcke, H., additional, Fender, R., additional, Hörandel, J., additional, Koopmans, L. V. E., additional, Mann, G., additional, Miley, G., additional, Röttgering, H., additional, Stappers, B. W., additional, Wijers, R. A. M. J., additional, Zaroubi, S., additional, van den Akker, M., additional, Alexov, A., additional, Anderson, J., additional, Anderson, K., additional, van Ardenne, A., additional, Arts, M., additional, Asgekar, A., additional, Avruch, I. M., additional, Batejat, F., additional, Bähren, L., additional, Bell, M. E., additional, Bell, M. R., additional, van Bemmel, I., additional, Bennema, P., additional, Bentum, M. J., additional, Bernardi, G., additional, Best, P., additional, Bîrzan, L., additional, Bonafede, A., additional, Boonstra, A.-J., additional, Braun, R., additional, Bregman, J., additional, Breitling, F., additional, van de Brink, R. H., additional, Broderick, J., additional, Broekema, P. C., additional, Brouw, W. N., additional, Brüggen, M., additional, Butcher, H. R., additional, van Cappellen, W., additional, Ciardi, B., additional, Coenen, T., additional, Conway, J., additional, Coolen, A., additional, Corstanje, A., additional, Damstra, S., additional, Davies, O., additional, Deller, A. T., additional, Dettmar, R.-J., additional, van Diepen, G., additional, Dijkstra, K., additional, Donker, P., additional, Doorduin, A., additional, Dromer, J., additional, Drost, M., additional, van Duin, A., additional, Eislöffel, J., additional, van Enst, J., additional, Ferrari, C., additional, Frieswijk, W., additional, Gankema, H., additional, Garrett, M. A., additional, de Gasperin, F., additional, Gerbers, M., additional, de Geus, E., additional, Grießmeier, J.-M., additional, Grit, T., additional, Gruppen, P., additional, Hamaker, J. P., additional, Hassall, T., additional, Hoeft, M., additional, Holties, H. A., additional, Horneffer, A., additional, van der Horst, A., additional, van Houwelingen, A., additional, Huijgen, A., additional, Iacobelli, M., additional, Intema, H., additional, Jackson, N., additional, Jelic, V., additional, de Jong, A., additional, Juette, E., additional, Kant, D., additional, Karastergiou, A., additional, Koers, A., additional, Kollen, H., additional, Kondratiev, V. I., additional, Kooistra, E., additional, Koopman, Y., additional, Koster, A., additional, Kuniyoshi, M., additional, Kramer, M., additional, Kuper, G., additional, Lambropoulos, P., additional, Law, C., additional, van Leeuwen, J., additional, Lemaitre, J., additional, Loose, M., additional, Maat, P., additional, Macario, G., additional, Markoff, S., additional, Masters, J., additional, McFadden, R. A., additional, McKay-Bukowski, D., additional, Meijering, H., additional, Meulman, H., additional, Mevius, M., additional, Middelberg, E., additional, Millenaar, R., additional, Miller-Jones, J. C. A., additional, Mohan, R. N., additional, Mol, J. D., additional, Morawietz, J., additional, Morganti, R., additional, Mulcahy, D. D., additional, Mulder, E., additional, Munk, H., additional, Nieuwenhuis, L., additional, van Nieuwpoort, R., additional, Noordam, J. E., additional, Norden, M., additional, Noutsos, A., additional, Offringa, A. R., additional, Olofsson, H., additional, Omar, A., additional, Orrú, E., additional, Overeem, R., additional, Paas, H., additional, Pandey-Pommier, M., additional, Pandey, V. N., additional, Pizzo, R., additional, Polatidis, A., additional, Rafferty, D., additional, Rawlings, S., additional, Reich, W., additional, de Reijer, J.-P., additional, Reitsma, J., additional, Renting, G. A., additional, Riemers, P., additional, Rol, E., additional, Romein, J. W., additional, Roosjen, J., additional, Ruiter, M., additional, Scaife, A., additional, van der Schaaf, K., additional, Scheers, B., additional, Schellart, P., additional, Schoenmakers, A., additional, Schoonderbeek, G., additional, Serylak, M., additional, Shulevski, A., additional, Sluman, J., additional, Smirnov, O., additional, Sobey, C., additional, Spreeuw, H., additional, Steinmetz, M., additional, Sterks, C. G. M., additional, Stiepel, H.-J., additional, Stuurwold, K., additional, Tagger, M., additional, Tang, Y., additional, Tasse, C., additional, Thomas, I., additional, Thoudam, S., additional, Toribio, M. C., additional, van der Tol, B., additional, Usov, O., additional, van Veelen, M., additional, van der Veen, A.-J., additional, ter Veen, S., additional, Verbiest, J. P. W., additional, Vermeulen, R., additional, Vermaas, N., additional, Vocks, C., additional, Vogt, C., additional, de Vos, M., additional, van der Wal, E., additional, van Weeren, R., additional, Weggemans, H., additional, Weltevrede, P., additional, White, S., additional, Wijnholds, S. J., additional, Wilhelmsson, T., additional, Wucknitz, O., additional, Yatawatta, S., additional, Zarka, P., additional, Zensus, A., additional, and van Zwieten, J., additional

Published
2013
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26. Wide-band simultaneous observations of pulsars: disentangling dispersion measure and profile variations

Author

Hassall, T. E., primary, Stappers, B. W., additional, Hessels, J. W. T., additional, Kramer, M., additional, Alexov, A., additional, Anderson, K., additional, Coenen, T., additional, Karastergiou, A., additional, Keane, E. F., additional, Kondratiev, V. I., additional, Lazaridis, K., additional, van Leeuwen, J., additional, Noutsos, A., additional, Serylak, M., additional, Sobey, C., additional, Verbiest, J. P. W., additional, Weltevrede, P., additional, Zagkouris, K., additional, Fender, R., additional, Wijers, R. A. M. J., additional, Bähren, L., additional, Bell, M. E., additional, Broderick, J. W., additional, Corbel, S., additional, Daw, E. J., additional, Dhillon, V. S., additional, Eislöffel, J., additional, Falcke, H., additional, Grießmeier, J.-M., additional, Jonker, P., additional, Law, C., additional, Markoff, S., additional, Miller-Jones, J. C. A., additional, Osten, R., additional, Rol, E., additional, Scaife, A. M. M., additional, Scheers, B., additional, Schellart, P., additional, Spreeuw, H., additional, Swinbank, J., additional, ter Veen, S., additional, Wise, M. W., additional, Wijnands, R., additional, Wucknitz, O., additional, Zarka, P., additional, Asgekar, A., additional, Bell, M. R., additional, Bentum, M. J., additional, Bernardi, G., additional, Best, P., additional, Bonafede, A., additional, Boonstra, A. J., additional, Brentjens, M., additional, Brouw, W. N., additional, Brüggen, M., additional, Butcher, H. R., additional, Ciardi, B., additional, Garrett, M. A., additional, Gerbers, M., additional, Gunst, A. W., additional, van Haarlem, M. P., additional, Heald, G., additional, Hoeft, M., additional, Holties, H., additional, de Jong, A., additional, Koopmans, L. V. E., additional, Kuniyoshi, M., additional, Kuper, G., additional, Loose, G. M., additional, Maat, P., additional, Masters, J., additional, McKean, J. P., additional, Meulman, H., additional, Mevius, M., additional, Munk, H., additional, Noordam, J. E., additional, Orrú, E., additional, Paas, H., additional, Pandey-Pommier, M., additional, Pandey, V. N., additional, Pizzo, R., additional, Polatidis, A., additional, Reich, W., additional, Röttgering, H., additional, Sluman, J., additional, Steinmetz, M., additional, Sterks, C. G. M., additional, Tagger, M., additional, Tang, Y., additional, Tasse, C., additional, Vermeulen, R., additional, van Weeren, R. J., additional, Wijnholds, S. J., additional, and Yatawatta, S., additional

Published
2012
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27. Scaling Astro-WISE to LOFAR long term archive

Author

Begeman, K., primary, Belikov, A. N., additional, Boxhoorn, D., additional, Dijkstra, F., additional, Holties, H. A., additional, Renting, G. A., additional, Vermaas, N., additional, and Vriend, W. -J., additional

Published
2012
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28. Optimized trigger for ultra-high-energy cosmic-ray and neutrino observations with the low frequency radio array

Author

Singh, K., primary, Mevius, M., additional, Scholten, O., additional, Anderson, J.M., additional, van Ardenne, A., additional, Arts, M., additional, Avruch, M., additional, Asgekar, A., additional, Bell, M., additional, Bennema, P., additional, Bentum, M., additional, Bernadi, G., additional, Best, P., additional, Boonstra, A.-J., additional, Bregman, J., additional, van de Brink, R., additional, Broekema, C., additional, Brouw, W., additional, Brueggen, M., additional, Buitink, S., additional, Butcher, H., additional, van Cappellen, W., additional, Ciardi, B., additional, Coolen, A., additional, Damstra, S., additional, Dettmar, R., additional, van Diepen, G., additional, Dijkstra, K., additional, Donker, P., additional, Doorduin, A., additional, Drost, M., additional, van Duin, A., additional, Eisloeffel, J., additional, Falcke, H., additional, Garrett, M., additional, Gerbers, M., additional, Grießmeier, J.-M., additional, Grit, T., additional, Gruppen, P., additional, Gunst, A., additional, van Haarlem, M., additional, Hoeft, M., additional, Holties, H., additional, Hörandel, J., additional, Horneffer, L.A., additional, Huijgen, A., additional, James, C., additional, de Jong, A., additional, Kant, D., additional, Kooistra, E., additional, Koopman, Y., additional, Koopmans, L., additional, Kuper, G., additional, Lambropoulos, P., additional, van Leeuwen, J., additional, Loose, M., additional, Maat, P., additional, Mallary, C., additional, McFadden, R., additional, Meulman, H., additional, Mol, J.-D., additional, Morawietz, J., additional, Mulder, E., additional, Munk, H., additional, Nieuwenhuis, L., additional, Nijboer, R., additional, Norden, M.J., additional, Noordam, J., additional, Overeem, R., additional, Paas, H., additional, Pandey, V.N., additional, Pandey-Pommier, M., additional, Pizzo, R., additional, Polatidis, A., additional, Reich, W., additional, de Reijer, J., additional, Renting, A., additional, Riemers, P., additional, Roettgering, H., additional, Romein, J., additional, Roosjen, J., additional, Ruiter, M., additional, Schoenmakers, A., additional, Schoonderbeek, G., additional, Sluman, J., additional, Smirnov, O., additional, Stappers, B., additional, Steinmetz, M., additional, Stiepel, H., additional, Stuurwold, K., additional, Tagger, M., additional, Tang, Y., additional, ter Veen, S., additional, Vermeulen, R., additional, de Vos, M., additional, Vogt, C., additional, van der Wal, E., additional, Weggemans, H., additional, Wijnholds, S., additional, Wise, M., additional, Wucknitz, O., additional, Yattawatta, S., additional, and van Zwieten, J., additional

Published
2012
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29. Observing pulsars and fast transients with LOFAR

Author

Stappers, B. W., primary, Hessels, J. W. T., additional, Alexov, A., additional, Anderson, K., additional, Coenen, T., additional, Hassall, T., additional, Karastergiou, A., additional, Kondratiev, V. I., additional, Kramer, M., additional, van Leeuwen, J., additional, Mol, J. D., additional, Noutsos, A., additional, Romein, J. W., additional, Weltevrede, P., additional, Fender, R., additional, Wijers, R. A. M. J., additional, Bähren, L., additional, Bell, M. E., additional, Broderick, J., additional, Daw, E. J., additional, Dhillon, V. S., additional, Eislöffel, J., additional, Falcke, H., additional, Griessmeier, J., additional, Law, C., additional, Markoff, S., additional, Miller-Jones, J. C. A., additional, Scheers, B., additional, Spreeuw, H., additional, Swinbank, J., additional, ter Veen, S., additional, Wise, M. W., additional, Wucknitz, O., additional, Zarka, P., additional, Anderson, J., additional, Asgekar, A., additional, Avruch, I. M., additional, Beck, R., additional, Bennema, P., additional, Bentum, M. J., additional, Best, P., additional, Bregman, J., additional, Brentjens, M., additional, van de Brink, R. H., additional, Broekema, P. C., additional, Brouw, W. N., additional, Brüggen, M., additional, de Bruyn, A. G., additional, Butcher, H. R., additional, Ciardi, B., additional, Conway, J., additional, Dettmar, R.-J., additional, van Duin, A., additional, van Enst, J., additional, Garrett, M., additional, Gerbers, M., additional, Grit, T., additional, Gunst, A., additional, van Haarlem, M. P., additional, Hamaker, J. P., additional, Heald, G., additional, Hoeft, M., additional, Holties, H., additional, Horneffer, A., additional, Koopmans, L. V. E., additional, Kuper, G., additional, Loose, M., additional, Maat, P., additional, McKay-Bukowski, D., additional, McKean, J. P., additional, Miley, G., additional, Morganti, R., additional, Nijboer, R., additional, Noordam, J. E., additional, Norden, M., additional, Olofsson, H., additional, Pandey-Pommier, M., additional, Polatidis, A., additional, Reich, W., additional, Röttgering, H., additional, Schoenmakers, A., additional, Sluman, J., additional, Smirnov, O., additional, Steinmetz, M., additional, Sterks, C. G. M., additional, Tagger, M., additional, Tang, Y., additional, Vermeulen, R., additional, Vermaas, N., additional, Vogt, C., additional, de Vos, M., additional, Wijnholds, S. J., additional, Yatawatta, S., additional, and Zensus, A., additional

Published
2011
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33. Observation of Multiple Kinetic Alfvén Eigenmodes

Author

Fasoli, A., primary, Lister, J. B., additional, Sharapov, S., additional, Borba, D., additional, Deliyanakis, N., additional, Gormezano, C., additional, Jacquinot, J., additional, Jaun, A., additional, Holties, H. A., additional, Huysmans, G. T. A., additional, Kerner, W., additional, Moret, J.-M., additional, and Villard, L., additional

Published
1996
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39. Target for LOFAR Long Term Archive: Architecture and Implementation

Author

Belikov, A., Boxhoorn, D., Dijkstra, Fokke, Holties, H. A., Vriend, W. -J, Ballester, P., Egret, D., Lorente, N. P. F., Lorente, N.P.F., and Astronomy

Subjects
ComputerApplications_COMPUTERSINOTHERSYSTEMS
Abstract

The LOFAR Long-Term Archive (LTA) is a multi-Petabyte scale data storage for the processed data of LOFAR telescope. We describe the adaptation of the WISE concept implemented by Target consortium for the LOFAR LTA and changes we introduced to it to accommodate LOFAR data. This paper describes an example of a new information system created on the basis of Astro-WISE for a wider range and scale of data.

43. Wide-band simultaneous observations of pulsars: disentangling dispersion measure and profile variations

Author

P. Maat, Benjamin Stappers, Heino Falcke, Charlotte Sobey, Emanuela Orrú, Jason W. T. Hessels, E. Rol, L. Bähren, H. Meulman, Joris P. W. Verbiest, C. Tasse, A. Alexov, Matthias Hoeft, M. A. Garrett, Sarod Yatawatta, James Miller-Jones, Evan Keane, Michael Kramer, S. ter Veen, J. Masters, A. W. Gunst, Casey J. Law, Jochen Eislöffel, B. Scheers, Maaijke Mevius, T. E. Hassall, J. W. Broderick, R. C. Vermeulen, B. Ciardi, Martin Bell, John McKean, Luitje Koopmans, J. E. Noordam, Gerard H. Kuper, Annalisa Bonafede, Harvey Butcher, Sera Markoff, M. P. van Haarlem, E. J. Daw, Rudy Wijnands, M. Kuniyoshi, V. I. Kondratiev, M. Pandey-Pommier, A. Noutsos, K. Zagkouris, Michael R. Bell, H. Paas, J. Sluman, Michiel A. Brentjens, Ashish Asgekar, Roberto Pizzo, Marcus Brüggen, C. G. M. Sterks, W. Reich, R. A. Osten, Albert-Jan Boonstra, Michel Tagger, Stephane Corbel, A. G. Polatidis, P.G. Jonker, M. Gerbers, Stefan J. Wijnholds, J. van Leeuwen, H. Spreeuw, A. de Jong, Matthias Steinmetz, R. J. van Weeren, P. Zarka, K. Lazaridis, George Heald, Mark J. Bentum, G. M. Loose, W. N. Brouw, Patrick Weltevrede, V. S. Dhillon, Aris Karastergiou, Michael W. Wise, Gianni Bernardi, M. Serylak, Rob Fender, Ralph A. M. J. Wijers, H. J. A. Röttgering, H. A. Holties, Y. Tang, Anna M. M. Scaife, Olaf Wucknitz, H. Munk, John D. Swinbank, Jean-Mathias Griessmeier, Vishambhar Pandey, Philip Best, Pim Schellart, T. Coenen, Kenneth C. Anderson, Kapteyn Astronomical Institute, Astronomy, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Netherlands Institute for Radio Astronomy (ASTRON), Max-Planck-Institut für Radioastronomie (MPIFR), Oxford Astrophysics, University of Oxford [Oxford], Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), University of Southampton, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), University of Sheffield [Sheffield], Thüringer Landessternwarte Tautenburg (TLS), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], Space Telescope Science Institute (STSci), School of Physics and Astronomy [Southampton], Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, University of Edinburgh, Jacobs University [Bremen], Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Leiden Observatory [Leiden], Universiteit Leiden [Leiden], National Radio Astronomy Observatory (NRAO), Applied Stochastics (IMAPP), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), Center for Information Technology CIT, Université de Groningen, Netherlands Foundation for Scientific Research. Joeri van Leeuwen and ThijsCoenen are supported by the Netherlands Research School for Astronomy (GrantNOVA3-NW3-2.3.1), European Project: 224838,EC:FP7:PEOPLE,FP7-PEOPLE-2007-4-3-IRG,PULSARS WITH LOFAR(2008), European Project: 236394,EC:FP7:PEOPLE,FP7-PEOPLE-IEF-2008,PULSAR SURVEY(2010), Hassall, T.E., Stappers, B.W., Hessels, J.W.T., Kramer, M., Alexov, A., Anderson, K., Coenen, T., Karastergiou, A., Keane, E.F., Kondratiev, V.I., Lazaridis, K., Van Leeuwen, J., Noutsos, A., Serylak, M., Sobey, C., Verbiest, J.P.W., Weltevrede, P., Zagkouris, K., Fender, R., Wijers, R.A.M.J., Bähren, L., Bell, M.E., Broderick, J.W., Corbel, S., Daw, E.J., Dhillon, V.S., Eislöffel, J., Falcke, H., Grießmeier, J.-M., Jonker, P., Law, C., Markoff, S., Miller-Jones, J.C.A., Osten, R., Rol, E., Scaife, A.M.M., Scheers, B., Schellart, P., Spreeuw, H., Swinbank, J., Ter Veen, S., Wise, M.W., Wijnands, R., Wucknitz, O., Zarka, P., Asgekar, A., Bell, M.R., Bentum, M.J., Bernardi, G., Best, P., Bonafede, A., Boonstra, A.J., Brentjens, M., Brouw, W.N., Brüggen, M., Butcher, H.R., Ciardi, B., Garrett, M.A., Gerbers, M., Gunst, A.W., Van Haarlem, M.P., Heald, G., Hoeft, M., Holties, H., De Jong, A., Koopmans, L.V.E., Kuniyoshi, M., Kuper, G., Loose, G.M., Maat, P., Masters, J., McKean, J.P., Meulman, H., Mevius, M., Munk, H., Noordam, J.E., Orrú, E., Paas, H., Pandey-Pommier, M., Pandey, V.N., Pizzo, R., Polatidis, A., Reich, W., Röttgering, H., Sluman, J., Steinmetz, M., Sterks, C.G.M., Tagger, M., Tang, Y., Tasse, C., Vermeulen, R., Van Weeren, R.J., Wijnholds, S.J., Yatawatta, S., University of Oxford, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Radboud University [Nijmegen], Harvard University-Smithsonian Institution, Universiteit Leiden, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Rhodes University, SKA South Africa, and Ska South Africa

Subjects
010504 meteorology & atmospheric sciences, Astronomy, Magnetosphere, Astrophysics, magnetic fields, 01 natural sciences, law.invention, law, Dispersion (optics), 010303 astronomy & astrophysics, Telescope, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, [PHYS]Physics [physics], Astrophysics::Instrumentation and Methods for Astrophysics, SPECTRAL BEHAVIOR, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Astrophysics - High Energy Astrophysical Phenomena, ARRIVAL-TIME DELAY, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, SUPERDISPERSION DELAY, EMPIRICAL-THEORY, Pulsar, pulsars: general, 0103 physical sciences, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, ISM: general, METIS-287956, Gravitational wave, Astronomy and Astrophysics, telescopes, LOFAR, Astronomy and Astrophysic, EWI-22107, Pulse (physics), PULSES, Interstellar medium, PSR 0809&74, FREQUENCY-DEPENDENCE, Magnetic field, Space and Planetary Science, [SDU]Sciences of the Universe [physics], RADIO-EMISSION, IR-80985, REFRACTION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], INTERSTELLAR SCATTERING
Abstract

Dispersion in the interstellar medium is a well known phenomenon that follows a simple relationship, which has been used to predict the time delay of dispersed radio pulses since the late 1960s. We performed wide-band simultaneous observations of four pulsars with LOFAR (at 40-190 MHz), the 76-m Lovell Telescope (at 1400 MHz) and the Effelsberg 100-m Telescope (at 8000 MHz) to test the accuracy of the dispersion law over a broad frequency range. In this paper we present the results of these observations which show that the dispersion law is accurate to better than 1 part in 100000 across our observing band. We use this fact to constrain some of the properties of the ISM along the line-of-sight and use the lack of any aberration or retardation effects to determine upper limits on emission heights in the pulsar magnetosphere. We also discuss the effect of pulse profile evolution on our observations, and the implications that it could have for precision pulsar timing projects such as the detection of gravitational waves with pulsar timing arrays., 20 Pages, 14 Figures, Accepted for publication in Astronomy & Astrophysics

Published
2012

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