A LOFAR Census of Millisecond Pulsars

With many thanks I refer to:

Kondratiev et al. 2015, "A LOFAR Census of Millisecond Pulsars"

http://arxiv.org/abs/1508.02948

http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1508.02948

Abstract: "We report the detection of 48 millisecond pulsars (MSPs) out of 75 observed thus far using the LOFAR in the frequency range 110-188 MHz. We have also detected three MSPs out of nine observed in the frequency range 38-77 MHz. This is the largest sample of MSPs ever observed at these low frequencies, and half of the detected MSPs were observed for the first time at frequencies below 200 MHz. We present the average pulse profiles of the detected MSPs, their effective pulse widths and flux densities, and compare these with higher observing frequencies. The LOFAR pulse profiles will be publicly available via the EPN Database of Pulsar Profiles. We also present average values of dispersion measures (DM) and discuss DM and profile variations. About 35% of the MSPs show strong narrow profiles, another 25% exhibit scattered profiles, and the rest are only weakly detected. A qualitative comparison of the LOFAR MSP profiles with those at higher radio frequencies shows constant separation between profile components. Similarly, the profile widths are consistent with those observed at higher frequencies, unless scattering dominates at the lowest frequencies. This is very different from what is observed for normal pulsars and suggests a compact emission region in the MSP magnetosphere. The amplitude ratio of the profile components, on the other hand, can dramatically change towards low frequencies, often with the trailing component becoming dominant. As demonstrated by Dyks et al. (2010) this can be caused by aberration and retardation. This data set enables high-precision studies of pulse profile evolution with frequency, dispersion, Faraday rotation, and scattering in the interstellar medium. Characterizing and correcting these systematic effects may improve pulsar-timing precision at higher observing frequencies, where pulsar timing array projects aim to directly detect gravitational waves."

LOFAR tied-array imaging and spectroscopy of solar S bursts

With many thanks I refer to Morosan et al. 2015

http://arxiv.org/abs/1507.07496

29 references at:
http://adsabs.harvard.edu/cgi-bin/nph-ref_query?bibcode=2015arXiv150707496M&refs=REFERENCES&db_key=PREhttp://adsabs.harvard.edu/cgi-bin/nph-ref_query?bibcode=2015arXiv150707496M&refs=REFERENCES&db_key=PRE

"Context. 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 hours. 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 MHz/s 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."

...

NenuFAR: The LOFAR Super Station project in Nancay

I refer to:

http://adsabs.harvard.edu/abs/2012sf2a.conf..687Z

Abstract: "We summarize the outcome of the scientific and technical study conducted in the past 3 years for the definition and prototyping of a LOFAR Super Station (LSS) in Nançay. We first present the LSS concept, then the steps addressed by the design study and the conclusions reached. We give an overview of the science case for the LSS, with special emphasis on the interest of a dedicated backend for standalone use. We compare the expected LSS characteristics to those of large low-frequency radio instruments, existing or in project. The main advantage of the LSS in standalone mode will be its very high instantaneous sensitivity, enabling or significantly improving a broad range of scientific studies. It will be a SKA precursor for the French community, both scientific and technical."

Poland will build 3 LOFAR stations

http://www.astron.nl/about-astron/press-public/news/three-new-antenna-stations-lofar-poland/three-new-antenna-stations-lo

"...ASTRON and the Polish LOFAR consortium POLFAR signed a contract for the construction of three new antenna stations for the International LOFAR Telescope (ILT) in the north, west and south of Poland. Signing of the contract took place at the University of Warmia and Mazury in Olsztyn in Poland in the presence of representatives of ASTRON, the Polish Ministry of Science and Higher Education and local governments, and representatives of the Polish astronomical and space sciences communities..."

"...At the end of 2013, POLFAR received a grant from the Polish Minister of Science and Higher Education for the construction and equipment of three international LOFAR stations as part of their national research infrastructure investment. The new LOFAR stations will be located in Łazy (in southern Poland, operated by the Jagiellonian University in Krakow), Bałdy (in northern Poland, operated by the University of Warmia and Mazury in Olsztyn), and Borówiec (in western Poland, operated by the Space Research Centre of the Polish Academy of Sciences). The formal agreement between the POLFAR consortium and ASTRON now marks the start of the preparations for the roll-out of these new stations..."


  
Above:
"...representatives of POLFAR and ASTRON at the LOFAR signing ceremony: Prof. Jerzy Jaroszewski (Vice Rector for Research of University of Warmia and Mazury), Prof. Andrzey Krankowski (University of Warmia and Mazury), Prof. Katarzyna Otmianowska-Mazur (coordinator of POLFAR, Astronomical Observatory of the Jagiellonian University), Dr. Marian Soida (Vice Director of the Astronomical Observatory of the Jagiellonian University in Kraków), Ronald Halfwerk (Director of AstroTec Holding, ASTRON), Ass. Prof. Hanna Rothkaehl (Space Research Center of Polish Academy of Sciences in Warszawa), Rene Vermeulen (Director of the ILT, ASTRON), Dr. Krzysztof Chyży (Astronomical Observatory of the Jagiellonian University) and Ass. Prof. Ewa Szuszkiewicz (Head of the Institute of Astronomy and Astrophysics of the Szczecin University)..."

Third LOFAR Data Processing School November 17-23 2014

I note an announcement from Michael Wise, ASTRON  The Netherlands Institute for Radio Astronomy, Dwingeloo Netherlands :

http://www.astron.nl/

http://www.astron.nl/about-astron/information-about-astron

http://www.astron.nl/about-astron/history-astron/history-astron

"...The Third LOFAR Data Processing School will take place on Nov. 17-23, 2014 at ASTRON in Dwingeloo, the Netherlands. The school will be hosted by the Radio Observatory at ASTRON and the LOFAR project.

LOFAR has entered its operational phase, and has started delivering scientific and unique data in the relatively unexplored spectral window below 200 MHz. At the present time, 46 operational stations are part of the LOFAR array, of which 38 are located in the Netherlands, and 8 are in Germany, France, Sweden and the United Kingdom. New stations will soon be built in Germany and Poland. In parallel, the first versions of several of LOFAR's science pipelines have been developed and are able to generate scientific data products to the numerous users who have obtained observing and processing time through the past and current Cycles.

As with the first two LOFAR data schools, the aim of this workshop is to introduce the LOFAR system to new members of the collaboration who will analyse Cycle data. Students, postdocs, and staff are all encouraged to attend. The school will cover the many aspects of the LOFAR system from the capabilities of the basic station hardware to the software pipelines and science products they produce. Lectures and tutorials will be presented by members of the LOFAR project team as well as staff from the many institutions involved in the collaboration. Hands-on sessions will also be provided to give attendees an opportunity to gain experience with real LOFAR data.

Presentations will be given at a level appropriate for someone new to LOFAR. Familiarity with the concepts of radio interferometry and standard data processing software such as CASA, AIPS, or Myriad will be useful, but not required. Minimum requirements should include some familiarity with scripting languages and in particular Python. Parallel sessions for more expert students are also planned.

Attendance will be limited to approximately 40 people. Initial preference will be given to applicants from teams with accepted Cycle projects. Space will however be reserved for applicants from the general astronomical community, so all potential LOFAR users are encouraged to apply.

Workshop attendees will be responsible for their own travel and accommodation costs while attending the workshop.

More details about the Third LOFAR Data Processing School will be circulated during the next few weeks. A registration form and methods of payment of the registration fee will be made available online.

You will be reminded by email to visit the website once the registration opens. In the meantime, please mark the dates in your calendars. We look forward to seeing many of you in the Autumn in Dwingeloo..."

LOFAR Science 2014 7-11 April 2014

I refer to:
http://www.astron.nl/lofarscience2014/

"The International LOFAR Telescope (ILT) consortium will host a week of meetings and workshops for the LOFAR community from April 7-11, 2014 in Amsterdam, The Netherlands. The week will begin on Monday afternoon with a LOFAR Users Meeting, open to the whole LOFAR community, organized by the Radio Observatory to provide a forum for users to both learn about the status of the array as well as provide feedback. Following the Users Meeting, the 2014 LOFAR Community Science workshop will kick off on Tuesday morning, April 8 and run through the end of the day on Wednesday, April 9. The week will conclude with a two-day worksop on April 10 and 11 devoted to discussing the status and scientific exploitation of LOFAR’s first all-sky survey, the Multifrequency Snapshot Sky Survey (MSSS). Participants can choose to attend one or both of the workshops when registering for the meeting and a two-tier registration fee is available depending on which option is selected."

van Haarlem and 191 collaborators 2013, "LOFAR: The LOw-Frequency ARray"

I refer to van Haarlem and 191 collaborators 2013, "LOFAR: The LOw-Frequency ARray":
http://adsabs.harvard.edu/abs/2013JInst...8P5012A

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."

Noyola Satyal Musielak 2013: "Detection of Exomoons Through Their Modulation of Exoplanetary Radio Emissions"

I refer to Noyola Satyal Musielak 2013: "Detection of Exomoons Through Their Modulation of Exoplanetary Radio Emissions"
http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1308.4184

Abstract: "In the Jupiter-Io system, the moon's motion produces currents along the field lines that connect the moon to the Jupiter's polar regions, where the radio emission is modulated by the currents. Based on this process, we suggest that such modulation of planetary radio emissions may reveal the presence of exomoons around giant planets in exoplanetary systems. The required physical conditions for the modulation are established and used to select potential candidates for exomoon's detection. A cautiously optimistic scenario of possible detection of such exomoons with the Long Wavelength Array (LWA) and the Low-Frequency Array (LOFAR) radio telescopes is provided."