SKA 2010
→
Europe/London
Whitworth Hall (University of Manchester)
Whitworth Hall
University of Manchester
Oxford street Manchester
M139PL
Joseph Lazio
(NRL/SPDO)
Description
SKA 2010 is intended to be in the spirit of previous SKA science and engineering meetings, which were influential in shaping the direction of the SKA. However, now that the SKA has entered the system design phase, this meeting will have a greater focus on system and engineering decisions, and their impact on the scientific observations to be conducted by the SKA.
SKA activity world-wide is gathering pace as the project moves towards funding and site decisions in a few years time. PrepSKA and its sub-system verification programs, TDP, SKADS, and the precursor and pathfinder projects, are all contributing to the body of knowledge needed for the costed system design and SKA implementation plan to be delivered at the end of PrepSKA. On the astronomical side, the SKA science case is being refined and deepened through the focus on multi-wavelength observations and science simulations being carried out around the world.
The aim of SKA2010 is to bring the astronomical and engineering community together to discuss:
* The latest astronomical results in SKA-relevant areas,
* The status of engineering studies for the SKA systems and sub-systems, and
* Design/science trade-off issues for the SKA.
The results of these discussions are likely to have substantial impact on the direction of the international project, including a possible revision of the science priorities for the SKA.
Participants
Adrian Fitzgerald
Adrian Tiplady
Ahmed El-makadema
Alan Pedlar
alberto sesana
Alessio Magro
Alex Turnbull
Allan Colquhoun
Andrei Lobanov
Andrew Faulkner
Andrew Jones
André Offringa
Anita Loots
Anne Green
Anne Trefethen
Anthony Page
Anthony Schinckel
Aris Karastergiou
Arnold van Ardenne
Arpad Szomoru
Athol Kemball
Aziz AhmedSaid
Ben Stappers
Bernard F Burke
Bernard Fanaroff
Bill Imbriale
Billy Adams
Bo PENG
Bob Dickman
Bob Este
Brent Carlson
Brian Boyle
Bruce Elmegreen
Bruce Veidt
Cade Wells
Cameron Kiddle
Carole Jackson
Casey Law
Chang-Hee Kim
Charles Copley
Charles McGruder
Charles Smith
Chau Ching Chiong
Chris Mayer
Chris Pritchet
Chris Shenton
Chris Williams
Clive Dickinson
Colin Greenwood
Colin Lonsdale
Corina Vogt
Dan Werthimer
Daniel Price
David DeBoer
David George
David Hindley
David Wheeler
David Zhang
Dayton Jones
Deborah Shepherd
Dimitrios Psaltis
Dion Kant
Dominic Ford
Douglas BOCK
Du Biao
Duncan Hall
Edwin Kanters
Elias Brinks
Eloy de Lera
Eric Wilcots
ETHAN J. SCHREIER
Eva Juette
Feng Wang
Filipe Abdalla
Francois Kapp
Gabriel Grigorescu
Garrelt Mellema
Gary Hovey
Gemma Janssen
Geoff Mason
Geoffrey Bower
George Heald
Georgina Harris
Ger de Bruyn
German Cortes
Giampaolo Pisano
Gie Han Tan
Graham Jenkin
Graham Newton
Grazia Umana
Griffin Foster
Hans Olofsson
Hans-Rainer Kloeckner
Hansik Kim
Hayden Rampadarath
Heino Falcke
Hiroyuki Nakanishi
Huub Rottgering
Ian Heywood
Ian Smail
Isak Theron
Jaap Bregman
Jacco van Loon
Jack Hickish
James Cordes
James M Anderson
Jan Geralt Bij de Vaate
Jane Greaves
Japie Ludick
Jason Hessels
Jasper Horrell
Jean-Pierre Macquart
Jeff Kern
Jeroen Stil
Jo Bowler
Joeri Van Leeuwen
Joern Geisbuesch
Johan Pragt
John Bunton
John Pokinko
John Webber
Jonathan Pritchard
Jongsoo Kim
Jose Enrique Ruiz del Mazo
Jose-Francisco Gomez
Joseph Lazio
Judd Bowman
Jugdutt (Jack) Singh
Justin Jonas
Kenneth Kellerman
Kiri Wagstaff
Kobus Cloete
Kristian Zarb Adami
Larry D'Addario
Leonid Gurvits
Lincoln Greenhill
Lisa Bell
Lisa Harvey-Smith
Lister Staveley-Smith
Lize van den Heever
LJ du Toit
Lynn Baker
Marcella Massardi
Marcus Ward
Mario Aldera
Mark Adams
Mark Sargent
Masaya Kuniyoshi
Matt Fleming
Matthew Bailes
Matthew Morgan
Melanie Johnston-Hollitt
Melvin Hoare
Michael Garrett
Michael Kramer
Michael Simmons
Michael Wise
Michiel van Haarlem
Mike Hook
Mike Jones
Minho Choi
Mo Missous
Monika Obrocka
Mário Santos
Neal Jackson
Neil Roddis
Nigel Rix
Noriyuki Kawaguchi
Oleg Smirnov
Paolo Padovani
Paolo Serra
Parisha Noorishad
Patricia Henning
Paul Alexander
Peter Dewdney
Peter Hall
Peter Kerney
Peter Matthewson
Peter Sarre
Peter Wilkinson
Philip Crosby
Philip Diamond
Pieter Stoffberg
Rainer Beck
Raj Mittra
Ralph Spencer
Ravi Subrahmanyan
Ray Norris
Reinhard Keller
Rene Vermeulen
Richard Armstrong
Richard Davis
Richard Schilizzi
Richard Whitaker
Rob Beswick
Rob Fender
Rob Millenaar
Robert Braun
Robert Preston
Roger Deane
Ron Ekers
Ronald Nijboer
Roshene McCool
Rosie Bolton
Roy Booth
Russ Taylor
Russell Gough
Ruud Overeem
Sang-Sung Lee
Sarah Burke
Sarah Burke Spolaor
Sascha Schediwy
Scott Ransom
Sean Dougherty
Sean McGuire
Sergei Gulyaev
Shaun Hendricks
Simon Garrington
Simon Johnston
Stefan Wijnholds
Stefano Salvini
Steve Rawlings
Steve Torchinsky
Steven Durand
Steven Myers
Steven Tingay
Swaminathan Natarajan
Thijs van der Hulst
Thomas Kusel
Tim Colegate
Tim Cornwell
Timothy Ikin
TL Venkatasubramani
Tom Oosterloo
Tony Beasley
Tony Brown
Ue-Li Pen
Verdes-Montenegro Lourdes
Vernon Pankonin
Walid Majid
Wallace Turner
Willem Esterhuyse
Wim van Cappellen
Wim van Driel
Yashwant Gupta
Yogesh Wadadekar
Yu Lu
Yuri Kovalev
Zsolt Paragi
Contact
-
- 1
- 2
- 3
-
Posters Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
10:35
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
International SKA Progress: Reports from PrepSKA Liason Engineers Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLLiason engineers from each institution participating in PrepSKA will provide brief reports on current status and recent progress.
-
12:30
lunch Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Science with the Pathfinders and the Route to the SKA Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL- 4
- 5
- 6
- 7
- 8
- 9
-
15:30
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Science with the Pathfinders and the Route to the SKA Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL- 10
- 11
- 12
- 13
- 14
-
- 15
- 16
-
Posters Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL - 17
-
10:30
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Panel Discussion on Dishes and Wide Band Single Pixel Feeds (WBSPFs) for the SKA-mid Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLPanelists will lead a discussion on Dishes and WBSPFs, touching on the scientific opportunities, capabilities, risks, and required computing and processing needs of this technology for the SKA-mid.
-
18
Opening Statements by Panelists
-
19
Open Discussion
-
18
-
12:30
lunch Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Panel Discussion on Dense Aperture Arrays for SKA-mid Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLPanelists will lead a discussion on Dense Aperture Arrays, touching on the scientific opportunities, capabilities, risks, and required computing and processing needs of this technology for the SKA-mid.
-
20
Opening Statements by Panelists
-
21
Open Discussion
-
20
-
15:00
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL - 22
-
Panel Discussion on Dishes+Phased Array Feeds (PAFs) for SKA-mid Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLPanelists will lead a discussion on Dishes and PAFs, touching on the scientific opportunities, capabilities, risks, and required computing and processing needs of this technology for the SKA-mid.
-
23
Opening Statements by Panelists
-
24
Open Discussion
-
23
-
Conference Dinner EastZEast Restaurant (Manchester)
EastZEast Restaurant
Manchester
Blackfriars Street Manchester, M3 2EGEast Z East
www.eastzeast.comBlackfriars Street
Manchester, M3 2EG
-
-
25
Paths to Learning about the First Luminous Sources with the SKA Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLSpeaker: J. Pritchard -
Parallel Sessions: SWG, OWG, Outreach, PITF, CTF, Antennas, Computing Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLCurrently scheduled: Science WG, Operations WG, Outreach WG, Power Investigation Task Force, Configurations Task Force, Antennas Design Group, Software and Computing Design Group
Working groups will meet either individually or jointly to discuss pending action items and issues and discuss progress toward the SKA system design.
- 26
- 27
-
28
Operations WG"open skies"; role of Regional Support Centers; issues affecting construction and operating cost; Operations Plan
-
29
Outreach WGTV and other media opportunities; e-newsletter updates/modifications
-
30
Power Investigation Task Forcecurrent status; implications of SKA configurations; power analyses; future steps
- 31
-
Posters Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
10:30
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Parallel Sessions: SWG, OWG, Outreach, PITF, CTF, Antennas, Computing Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLCurrently scheduled: Science WG, Operations WG, Outreach WG, Power Investigation Task Force, Configurations Task Force, Antennas Design Group, Software and Computing Design Group
Working groups will meet either individually or jointly to discuss pending action items and issues and discuss progress toward the SKA system design.
-
32
Antennas Design Group
-
33
Computing Design Groupsoftware development strategy; telecons
-
34
Configurations Task Force
-
35
Operations WG"open skies"; role of Regional Support Centers; issues affecting construction & operating cost; Operations Plan
-
36
Outreach WGTV & other media opportunities; e-newsletter updates/modifications
- 37
- 38
-
32
-
12:30
lunch Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Contributed Engineering Talks Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL-
39
R&D, Manufacture and Installation for ASKAP and DVAC Primary DesignCETC54 experiences of ASKAP (Australian Square Kilometre Array Pathfinder) antenns mass production from design, manufactureing to commission in unattended area are firstly presented. The primary design of DVAC (Chinese Dish Verification Antenna) is introduced based on SKA Dish Verification Antenna System Functional Specifications. The R&D, construction and commission experiences of other radio telescope antennas are also described.Speaker: Prof. Biao Du (The 54th Research Insitute of China Electronics Technology Group Corporation (CETC54))
-
40
Numerical Simulation of Some Antenna Systems for the Square Kilometer Array Project—Challenges and SuccessesIn this paper we discuss the problem of rigorous simulation of some of the potential candidates for the antenna designs being considered for the Square Kilometer Array (SKA) project. These include large arrays of wideband elements, such as Vivaldis that are mounted on complex structures, as well as reflector antenna systems with patch array feeds and support systems, e.g., struts. Accurate prediction of the impedance characteristics as well as of the radiation patterns---including the wide angle sidelobe levels---is extremely important in the design stage, when many options must be weighed in and factored into the process of developing optimal configurations from the point of view of overall performance. Because of the large electrical size of the overall system, whose dimensions are in the range of tens or even hundreds of wavelengths, rigorous calculations of the near and far field parameters require extensive computing resources, equipped with a large number of processors, access to substantial memory and adequate CPU time. Hence, such problems can only be handled on a parallel computing facility. However, computing resources alone are not adequate for the task, and availability of the "right" CEM code, which scales well on parallel platforms is the key to successful modeling of the large and multiscale type of problems that need to be analyzed for the SKA project. We should also mention that most of the available commercial CEM tools are found to be woefully inadequate for the task, because they do not scale well when parallelized. For the problems at hand, the simulations are typically carried out on a supercomputer with more than 3000 compute nodes, each consisting of 4 cores and 2GB of memory. The parallelized Finite-Difference Time-Domain (FDTD) software package GEMS, which is enabled with the Message Passing Interface Library, has been adopted to carry out the simulations, since it is capable of handling electrically large and complex systems with very high accuracy and numerical efficiency, and it exhibits excellent scaling properties on large computer clusters. Extensive results will be included in the presentation to illustrate both the challenges and successes encountered in the course of the studies of SKA antennas that we have carried out during the last four years.Speaker: Dr Raj Mittra (EMC Laboratory, Pennsylvania State University)
-
41
Kneeling down standing waves with APERTIF phased array feeds in the WSRTAPERTIF is an SKA Pathfinder aiming to increase the survey speed of the Westerbork Synthesis Radio Telescope (WSRT) with a factor 20. With APERTIF, Phased Array Feed (PAF) systems will be installed on most of the WSRT dishes. A commonly observed effect plaguing wideband prime-focus reflector systems is an interaction between the feed and the reflector, commonly referred to as the ‘standing wave’ phenomenon. For the WSRT, it results in a beam pattern and sensitivity variation as function of observing frequency with a period of ~17 MHz. Consequently, the observed spectra are distorted and because the beam pattern variations are unequal for the X and Y polarized beams, a frequency dependent instrumental polarization is introduced as well. Both effects limit the accuracy of polarimetric measurements and the dynamic range of the resulting images. Initial measurements of an APERTIF prototype in a WSRT dish hinted that the standing wave effect was reduced significantly compared to the existing horn feeds. This would have a major impact on the offline calibration: In the presence of the 17 MHz ripple the calibration of the beamshape would have to be repeated every ~1 MHz in order to adequately characterize the beam pattern. If the ripple is sufficiently reduced, the beam pattern variation is much smoother and can be described by less parameters. In this case the computational load of the offline calibration can be reduced and its accuracy is increased. A series of measurements has been performed to confirm the absence of the standing wave effect in the APERTIF prototype. The sensitivity of individual PAF elements, on-axis and scanned compound beams have been measured and the aperture field has been determined using holography. In this contribution we would like to present these recent experimental results which demonstrate that the 17 MHz ripple is largely eliminated in the PAF system.Speaker: Mr Wim van Cappellen (ASTRON)
-
42
Optics Design for the SKA Reflector Antennas with Wide-Band Single Pixel FeedsAs the next generation radio telescope, the Square Kilometer Array aims to have a combined sensitivity and survey speed several orders of magnitude larger than any current astronomical instrument. Operating over a extremely wide frequency band, from 100 MHz to 10 GHz, in its initial configuration, it relies on different technologies to cover the band: aperture array (both, sparse and dense) will be used in the low frequency range, from 100 MHz to 300 MHz, while for the medium to medium-high frequency range, from 300 MHz to 10 GHz in the current plan, it will use dishes with wide band single pixel feeds, with the possibility of utilizing focal phased arrays in the lower portion of this sub-band and with the same optics. The key aspects that will make possible the expected performance of the Square Kilometer Array are a high aperture efficiency, low system noise temperature and high dynamic range. These aspects are addressed in the optical design of the reflector antenna carried out by the US SKA Technical Development Project. We are going to present the main results of the TDP optical design effort, including an overview of the feed options, and the performance characteristics of the offset shaped optics design in terms of antenna gain, noise temperature, sidelobe levels, and Aeff/Tsys.Speaker: Dr German Cortes (Cornell University, Ithaca, NY, USA)
-
43
Industrial Commissioning of the SKA: Learning from the ALMA, EVLA and MeerKAT experiencesThe Square Kilometer Array will be a radio telescope with roughly one million square metres of collecting area designed to study the universe with unprecedented speed and sensitivity. Effectively commissioning an array of instrumentation that will support the SKA design goals will be a daunting task both in terms of the timescale needed to bring new equipment on-line and in terms of developing the competence and organizational framework needed to support this effort. To reduce the schedule risk and meet this challenge head on, we are developing a commissioning model from the earliest deployment stages of the project with rapid commissioning in mind. ALMA and EVLA commissioning projects are in full swing and we have applied key components of their commissioning models to the KAT-7 array, the precursor to the MeerKAT pathfinder. MeerKAT will bring 80 antennas on line in 2012 and 2013 at a rate of just over 3 antennas/month – a good test of potential SKA commissioning concepts. In this talk I will describe the development of the MeerKAT industrialized commissioning process and how this could be applied to the SKA.Speaker: Dr Deborah Shepherd (NRAO & SKA SA)
-
44
Support and Maintenance Requirements and Cost ModellingA methodology is introduced to derive support and maintenance requirements for the SKA telescope system. These requirements are used to develop operational, support and maintenance models for SKA construction and operational phases, and can be used in design decision making. The models are optimised for a variety of scientific and cost metrics that will be introduced, and result in an operational cost profile for the SKA system that meets availability requirements, as a function of the input science case.Speaker: Dr Adrian Tiplady (SKA South African)
-
45
System Engineering for SKA – special changes to classical SE processes to allow for the R&D nature of the SKAThe high R&D content combined with the high volume production nature of projects such as the SKA presents special challenges to the system engineering process. The process must be tailored to allow emerging technologies to be incorporated into the programme during development. At the same time, the process must ensure that production baselines are frozen sufficiently early to reduce implementation risk. This paper presents an approach to tailoring the system engineering approach for such projects, based on the learning from the MeerKAT project.Speaker: Mr Thomas Kusel (SKA SA System Engineer)
-
46
The new, improved SKAcost: Design solutions from 70 MHz to 10 GHzWe present some new telescope design solutions in "SKAcost" which incorporate all the receptor types under consideration for the Square Kilometre Array. The SKA Reference Design is a result of several years of science-engineering interaction and includes aperture arrays, and dishes with phased array feeds and/or single-pixel feeds, as receptors. The final mix of receptor types will be an outcome of PrepSKA, so there is an imperative to understand how performance characteristics and costs scale as the design changes. We highlight SKAcost's capability as a systems engineering tool by illustrating some of these trade-offs. We extend the work of SKA Memo 100 to reflect current thinking and demonstrate new features of SKAcost, such as tracking power and easily identifying dominant component and subsystem costs. We show alternative solutions for the long baseline component of the SKA as an example of the flexibility of the designs. Additionally, we give examples of models presently being updated with information from SKA technology demonstrators such as ASKAP and the MWA, and indicate the future direction and uses for SKAcost.Speaker: Mr Tim Colegate (International Centre for Radio Astronomy Research / Curtin University)
-
39
-
15:30
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Signal Transport, Signal Processing, Software, & Data Management Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL-
47
Lessons from ALMA Software DevelopmentThe Atacama Large Millimeter/Submillimeter Array (ALMA) is among the largest ground-based astronomical projects undertaken to date. The SKA will face many of the same challenges as ALMA: development in a distributed environment, deployment in a remote location, and a large international collaboration plus the technical challenges of building a complex, flexible and cutting edge instrument. I will present a few of the lessons learned thus far during the construction of ALMA, both technical and managerial, and some strategies for addressing similar issues in the design and construction of the SKA.Speaker: Dr Jeff Kern (NRAO / ALMA)
-
48
Design of a Software Correlator for the Phase I SKAPhase I of the SKA will comprise of about 10% of the final collecting area. It is likely that a software correlator will be used for early science. Assuming 300 antennas, 4 GHz bandwidth, and two polarizations, the required performance of the software correlator for auto and cross correlations is 5.76 Peta FLOPS (Floating Operations Per Second), which is just about three times larger than that of the current fastest supercomputer in the world. Considering the near future technology developments, we designed the software correlator based on a cluster with multi-core processors and possibly graphic processing units (GPUs). Since the data rate from an antenna with a single pixel feed is 64 Gbit/sec (two polarizations, 4bit Nyquist sampling of 4 GHz bandwidth), a simplest possible network topology between antennas and computer nodes is point-to-point connections with 100 Gbit/sec ethernet. Due to the increase of number of bit for a sample after its fourier transform, the bandwidth of interconnections of computer nodes might be 4 or 8 times larger than the input data rate to each node. The cluster is composed of 300 computer nodes, and the performance of each node should be better than about 20 Tera FLOPS. We also estimated the expected performance, cost, and power usage of a 300 node GPU cluster with current technology.Speaker: Dr Jongsoo Kim (University of Cambridge)
-
49
Addressing scalability challenges in Monitoring and ControlThis presentation identifies scalability challenges associated with Monitoring & Control and some possible solution approaches. • Automated control and coordination of distributed, heterogenous elements. Guiding architectural principle: semi-autonomous control, where parent nodes specify objectives and child nodes work out how to achieve objective given local constraints. Provide facilities within the automated control scripts for dealing with heterogeneity and for situation handling. • Automated fault detection and handling. Approach: Fault detection algorithms at each level of the system hierarchy, and associated handling actions to achieve the defined objectives if at all possible while preserving system integrity. Fault detection at multiple time horizons (level 1 / level 2 level 3 feedback control) for early detection of problem situations based on behaviour patterns. • Automated system upgrade, with local constraints that necessitate staggering of upgrades and interoperation of different versions. Guiding architectural principle: version at parent node must be same or newer than version at child node. • Operator monitoring and control of huge numbers of elements. Guiding architectural principles: Minimize required interventions. Enable status-at-a-glance summary views with drill-down. Create rules for prevention and handling of conflict among operators at different levels of the system. • System management. Need to understand the behaviour of parts, their integration, and the system as a whole, in order to continuously improve and optimize the system. Approach: Automated analysis of logs and engineering data to develop models of system behaviour and detect potential problems and optimization opportunities. What-if analysis of resulting models to select optimizations, including cost reduction opportunities. • Software maintenance and evolution costs, agility. Guiding architectural principles: Use common software across the system as much as possible. Leverage public domain and COTS components, and make it easy to integrate future COTS software. Use specification-driven approaches and plug-ins to increase agility. • System rollout and evolution. Need to support phased construction and deployment. Guiding architectural principles: Specification-driven controllers that can be configured to accommodate control of any type of system element. Hierarchical modular approach to system control based on semi-autonomy, so that only controllers at the integration point need to be modified to accommodate new system elements. • Engineering properties. Achievement of performance, reliability, availability and security goals. Approach: Toolsets for automated analysis of engineering properties, and calibration of engineering models based on acquired data about system behaviour.Speaker: Dr Swaminathan Natarajan (Tata Research Development & Design Centre, Tata Consultancy Services)
-
50
Machine Learning for Real-Time Transient DetectionThe Square Kilometer Array (SKA) poses complex new challenges for high time resolution observations. The traditional operational approach of archiving and analyzing the data offline will not be possible given the unprecedented data rates that will be generated by the SKA. We are developing machine learning methods that exploit learned statistical properties of the data stream to enable large-scale signal analysis and anomaly detection in real-time. One application is the detection of fast transient pulses with millisecond (or less) duration. Data surrounding anomalous transient events can be saved, if they can be detected quickly enough (before the data buffer is overwritten with new data). In contrast to existing dedispersion searches that evaluate the signal at the same series of dispersion measures (DMs) for all data, our approach uses an adaptive strategy that selects likely DMs based on the particular signal being analyzed. This adaptive approach is able to dramatically reduce the required computational cost and shows great promise in keeping up with the anticipated SKA data rates. We have evaluated the adaptive and traditional approaches in a variety of computational cost regimes, motivated by the performance characteristics of different hardware components. We have also identified other areas in which machine learning methods can contribute to SKA data analysis, such as RFI excision and source type classification, and we plan to explore how these methods can be extended to other domains such as optical astronomy.Speaker: Dr Kiri Wagstaff (Jet Propulsion Laboratory, California Institute of Technology)
-
51
LOFAR offline interference detectionThe LOFAR telescope embeds various techniques to deal with radio frequency interference (RFI). One of these techniques is a completely automated post-correlation flagger. For this purpose, several post-correlation classification methods for efficient detection and flagging of RFI have been designed and compared. Currently, the selected flagging strategy is the “SumThreshold” method, which consists of an iterative surface fit in the time frequency plane and a new combinatorial thresholding technique. Several tweaks can enhance speed, quality and purpose, for example, to allow pulsar data to be flagged. Scaling various RFI flagging methods, such as flagging on auto instead of cross-correlations, to the large number of stations projected for the SKA, requires some further thoughts. Some ideas about this will be presented.Speaker: Mr André Offringa (Kapteyn Astronomical Institute)
-
52
Direction-Dependent Effects in High-Dynamic Range WSRT Observations & The Availability Of SKA Calibration BeaconsThe WSRT is a very "dynamic range-friendly" instrument due to its design (equatorial mounts, stable beams & pointings, tiny closure errors), and is capable of achieving over a million dynamic range in a single 12-hour run with regular selfcalibration. Still, even the best WSRT maps show significant artifacts from direction-dependent effects (DDEs) that selfcal does not address. At 21cm, these are thought to be caused by pointing errors, tropospheric refraction, etc. The severity of WSRT's DDEs ranges from "luxury problem" (continuum observations) to "limiting factor" (spectral line work.) I will present the results of a "differential gains" calibration of the field around the bright source 3C147. This achieves the same 1.5+ million dynamic range as regular selfcal with the NEWSTAR package (previous reported by Ger de Bruyn), while completely removing the off-axis artifacts associated with direction-dependent effects: http://www.astron.nl/dailyimage/index.html?main.php?date=20100215. Surprisingly, a study of the differential gain solutions (http://www.astron.nl/dailyimage/index.html?main.php?date=20100223) suggests that the dominant source of direction-dependent errors in this particular observation is of global origin (i.e. not a pointing problem), and much stronger than we would expect from the troposphere! The DDEs show both a global amplitude and phase effect; the phase component is extremely well-fitted by a time-variable gradient over the array. We do not yet have an alternative explanation for the gradient (though this may well change by the time of the conference...) Whatever the source of WSRT DDEs, this result is of extremely high relevance to SKA calibration. SKA will require precise estimation of DDEs, which in turn requires a grid of calibration "beacon" sources that can be used to fit for the parameters of beamshapes, ionosphere, etc. At higher frequencies, the availability of sufficient numbers of sufficiently bright beacons is a worry. Differential gain solutions around 3C147 show that even relatively weak (~10 mJy) sources provide enough S/N, thus significantly lowering the bar on potential beacons.Speaker: Dr Oleg Smirnov (ASTRON)
-
53
Imaging with the SKA coreThe moderate resolution and high brightness sensitivity of the SKA core may be exploited to study the diffuse structures in our Galaxy, the IGM and the cosmic web. The combination of high sensitivity and moderate resolution leads to confusion limited maps at each frequency from which the source components along each line-of-sight may be extracted by exploiting the difference in spectral characteristics of the individual sources. This extraction can only be successful if the individual maps are made using a reliable and consistent method. Least squares imaging has several attractive features that make it well suited for imaging with the SKA core: - The model based imaging (deconvolution) problem can be solved in closed form [1]. - The closed form solution for the complete grid of pixels in the image is mathematically identical to the solution for simultaneous source power estimation in the self-calibration process (see [4]), which should facilitate integration of the calibration and imaging processes. - The availability of a closed form solution allows for a complete error and noise propagation analysis [3]. - It implicitly handles arbitrary direction dependent effects that may vary over time and frequency during the observation [1]. - The numerical complexity of the deconvolution operation only depends on the number of image parameters regardless of the amount of visibility data [1]. - It has been demonstrated that the algorithm reaches the Cramer-Rao bound on actual data [2]. The Cramer-Rao bound is the lower bound on the total variance on the estimated parameters for an unbiased estimator. In this presentation I discuss the strengths and weaknesses of l_2-based image optimization to demonstrate its suitability for imaging with the SKA core. I illustrate this by application to actual LOFAR data. I also discuss the numerical complexity of the algorithm demonstrating that this is a viable option for imaging with the SKA core. References [1] Stefan J. Wijnholds, Fish-Eye Imaging With A LOFAR Station. In Proceedings of the International Union of Radio Science (URSI) Benelux Forum, Delft, The Netherlands, 8 June 2009. [2] Stefan J. Wijnholds, Least Squares All-Sky Imaging With A LOFAR Station. In SKA Calibration and Imaging Workshop (CalIm), Socorro (New Mexico), USA, 30 March - 3 April 2009. [3] Stefan J. Wijnholds and Alle-Jan van der Veen, Fundamental Imaging Limits of Radio Telescope Arrays. IEEE Journal of Selected Topics in Signal Processing, 2(5):613-623, October 2008. [4] Stefan J. Wijnholds and Alle-Jan van der Veen, Multisource Self-calibration for Sensor Arrays. IEEE Transactions on Signal Processing, 57(9):3512-3522, September 2009.Speaker: Dr Stefan Wijnholds (ASTRON)
-
54
Imaging and Beamforming Schemes for large-N aperture ArraysIn this work, I will present a summary of the beamforming techniques, both in the RF and in the digital domain used for aperture arrays in the SKA. In particular I will show results of the Two-Polarisation All-Digital (2-PAD) Aperture Array demonstrator designed and built in the UK as part of SKADS. Further to this, I will present new techniques including the Fast-Fourier Transform Telescope and the MOFF correlator which allow traditional imaging and calibration techniques to scale as NlogN rather than N^2. I will show how these techniques are being investigated on 2-PAD and on new science-capable demonstrators (specifically in the EoR and H1-precision cosmology regime) that will be built in the US as well as on one of the representative sites.Speaker: Dr Kristian Zarb Adami (University of Oxford)
-
47
-
25
-
- 55
-
Contributed Talks Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL-
56
The SKA Molonglo Prototype (SKAMP) Project – progress and first resultsThe Square Kilometre Array Molonglo Prototype (SKAMP) is a project using innovative technologies to transform the scientific capabilities of the University of Sydney's Molonglo Radiotelescope, located outside Canberra. The goal is to replace the whole signal chain to produce a dual-polarisation spectrometer operating in the band 700 – 1100 MHz with an instantaneous operating bandwidth of about 100 MHz. The angular resolution of the telescope is unchanged at 45”. Spectral resolution will be 14 kHz per channel (5km/sec at 843 MHz) and continuum source sensitivity will be about 150 microJansky/beam. Key science goals will be a survey of redshifted HI to test models of galaxy assembly, the transient radio sky and studies of cosmic magnetism. A progress report is presented and some preliminary results.Speaker: Prof. Anne Green (University of Sydney)
-
57
The SKADS White Paper: Aperture Arrays for the SKAThe SKADS White Paper is the consolidation of the work within SKADS and proposes an SKA system design which meets most of the science experiment requirements. The SKADS-SKA includes aperture array technology developed in SKADS, integration with dish collectors, and correlation and central processing scaling and implementation. The SKADS-SKA design is optimized for cost and performance. The technologies required on the timescale of the SKA are roadmapped using industrial consortia information e.g. the whole of the semiconductor industry. The potential risks associated are identified. The conclusion is that a very high performance SKA can be implemented that meets the principal science experiment requirements and also has the flexibility to make discoveries as yet unknown.Speaker: Dr Andrew Faulkner (University of Cambridge)
-
58
LOFAR: reasons to be cheerful pt. 3The Low Frequency Array is a new radio telescope that offers a number of unique and innovative capabilities for the astronomical community. These include dynamic real-time processing, rapid response to triggers and independent parallel observations with multiple beams. Construction and commissioning of the array is well underway. When completed, LOFAR will consist of 36 stations located in the North-East of the Netherlands and a total of at least 8 stations in Germany, France, the United Kingdom and Sweden. LOFAR makes use of many technologies under consideration for the Square Kilometre Array: phased array antenna stations with both analogue and digital beamforming, flexible high speed digital signal processing and extensive software development resulting in automated processing pipelines that deliver science products to its users. Involvement in complex collaborations with both academic and industrial partners, multiple public procurement rounds and experience with mass production and the logistics of system integration should all prove useful for the SKA project. LOFAR has also needed to find a balance between scientific scope, technical feasibility and financial boundary conditions, which the SKA now also has to grapple with.Speaker: Dr Michiel van Haarlem (ASTRON)
-
56
-
Posters Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
10:30
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Precursor and Verification Program Status Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PLCurrent status of the Precursor projects and the Verification programs and their deliverables to the SKA.
-
59
The Australian SKA Pathfinder - ASKAPThe Australian SKA Pathfinder is a new-generation radio telescope now under construction at a pristine site in Western Australia, the Murchison Radio-astronomy Observatory (MRO). ASKAP will trial innovative wide-field-of-view technology to achieve the fastest survey speed at the key frequency band around 1 GHz. International Science Survey Teams have been organized to plan and development the methods and techniques to achieve an ambitious set of scientific goals. ASKAP will be operational in early 2013.Speaker: Dr David DeBoer (CSIRO)
- 60
- 61
- 62
-
59
-
12:30
lunch Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL - 63
-
Contributed Science Talks Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL-
64
Long baseline science for the SKA and technical requirementsI will present an overview of the long baseline science for the SKA and translate the science goals into proposed technical requirements. I will also make comments regarding the possible implementation of the long baseline SKA, with a focus on gradual deployment of resources in alignment with existing infrastructure.Speaker: Prof. Steven Tingay (International Centre for Radio Astronomy Research)
-
65
The evolution of IR-radio relation for AGN hosts and starbursts at intermediate and high redshift in the COSMOS fieldThe IR/radio properties of galaxies at successively higher redshift have been probed in the past decade using either statistical samples from cosmological survey fields or dedicated samples of specific objects (e.g. sub-mm galaxies). I will mention how the galaxy populations targeted by current radio surveys compare with those that the SKA could detect and briefly discuss -- following the presentation in Murphy et al. 2009 -- how studies of the IR-radio relation using SKA are expected to place constraints on the properties of the ISM of high-redshift galaxies. Based on the VLA-COSMOS 1.4 GHz and S-COSMOS 24 & 70 um observations of the 2 sqdeg COSMOS field I will present our measurements of the (non-)evolution of the IR-radio relation out to high redshift. In our analysis we employ the methods of survival analysis in order to ensure a statistically sound treatment of flux limits arising from non-detections. This allows us to study a volume-limited sample of ULIRGs at z<2 with which we provide firm support for previous findings that the IR-radio relation has remained unchanged in IR-bright galaxies since the peak of cosmic star formation activity. Furthermore, we determine the observed shift in average IR/radio properties of IR- and radio-selected populations and I will show that it can reconcile apparently discrepant measurements of the average IR/radio ratio of distant galaxies presented in the literature. Finally, and if time allows, I will also touch on our recent measurements of average IR/radio ratios for mass-selected COSMOS galaxies using IR and radio image stacking which probes LIRG luminosities out to z~2.Speaker: Dr Mark Sargent (MPIA Heidelberg)
-
66
Taking a Radio Census of Binary Supermassive Black HolesWe present a study that uses very long baseline interferometry to search for binary supermassive black holes at galaxy centres. Such searches are important in experimentally addressing the possibility that supermassive binaries may ``stall'', and never coalesce after the merger of their host galaxies; this would have dramatic (and likely detrimental) consequences for predicted gravitational wave signals and hierarchical galaxy formation alike. We have identified only one binary in a large sample of ~3000, suggesting observational evidence against stalling and putting a limit on the post-merger inspiral time of a supermassive black hole. Conclusive measurements of this kind will require observations of a great number of galaxies with long baselines, moderate sensitivity, and thorough u,v coverage. This science is therefore ideally fit for the SKA if it includes very-long-baseline capabilities; as such we detail the necessary components for a future study with the SKA.Speaker: Mrs Sarah Burke Spolaor (Swinburne University)
-
67
The spatial distribution of cold gas in hierarchical galaxy formation modelsThe distribution of cold gas in dark matter haloes is driven by key processes in galaxy formation: gas cooling, galaxy mergers, star formation and reheating of gas by supernovae. We compare the predictions of four different galaxy formation models for the spatial distribution of cold gas. We find that satellite galaxies make little contribution to the abundance or clustering strength of cold gas selected samples, and are far less important than they are in optically selected samples. The halo occupation distribution function for central galaxies is peaked around a halo mass of 1.e+11/hM⊙, a scale that is set by the AGN suppression of gas cooling. The model predictions for the projected correlation function are in good agreement with the estimate of Meyer et al. We compare the effective volume of possible surveys with the Square Kilometre Array with those expected for an redshift survey in the near-infrared. Future redshift surveys using neutral hydrogen emission will be competitive with the most ambitious spectroscopic surveys planned in the near-infrared.Speaker: Mr Hansik Kim (Durham University)
-
68
Wide-Bandwidth Polarimetry with the Allen Telescope ArrayNew kinds of feed design and signal processing are opening new domains in wide-bandwidth polarimetry. Wide, continuous bandwidths are particularly powerful when applied to the study of rotation measure. Mixed emitting and Faraday-rotating media can create complex frequency structure in the polarization properties of radio sources; such complexities can confuse narrow-bandwidth observations. We test and demonstrate the polarimetry capabilities of the Allen Telescope Array, a 42-element radio interferometer located in northern California. We show results from a rotation measure study of roughly 40 compact, bright polarized sources throughout the sky from 1.0 to 2.0 GHz. We establish a calibration procedure and measure the ATA's systematic polarization properties. While most rotation measures correlate well with narrow-band observations, there are a few noteworthy outliers.Speaker: Dr Casey Law (UC Berkeley)
-
64
-
15:25
coffee Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL -
Contributed Science Talks Whitworth Hall
Whitworth Hall
University of Manchester
Oxford street Manchester M139PL-
69
Early LOFAR Imaging ResultsLOFAR is growing rapidly, with more than 21 stations operating in the field, including 3 German stations, and the correlator routinely providing high quality interferometric data from those stations. The commissioning of the telescope is underway. During the past several months, the Imaging Pipeline has been undergoing exhaustive testing and development. I will describe our most recent challenges and successes in imaging the low-frequency sky at sub-arcminute resolution over many square degrees. Our progress will be described with a strong emphasis on some highlighted science topics that these images will enable (namely, all-sky surveys and cosmic magnetism). Finally, I will discuss some 'lessons learned' that can be applied to the first phases of the SKA.Speaker: Dr George Heald (ASTRON)
-
70
21 cm Cosmology From a micro-SKAFor the first time, observations targeting the highly redshifted 21 cm line have yielded a meaningful probe of neutral hydrogen in the intergalactic medium during the epoch of reionization. The Experiment to Detect the Global Epoch of Reionization Signature (EDGES) has measured the all-sky radio spectrum between 100 and 200 MHz with 10 mK sensitivity at the Murchison Radio-astronomy Observatory (MRO). Preliminary analysis of these measurements has ruled out very rapid reionization histories between redshifts 6 and 13. I will present the latest results and plans for future studies.Speaker: Dr Judd Bowman (Caltech)
-
71
Prospects for gravitational wave detection with pulsar timing arraysIn the next decade the detection of gravitational waves (GW) will be a reality, opening a completely new window on the Universe. Massive black holes (MBH) binaries (MBHBs) are expected to be among the primary actors on this upcoming stage. Utilizing detailed MBHB population models (based on our current best understanding of galaxy formation and evolution trough mergers, and on our knowledge of the relations between MBHs and their hosts), I describe prospects of detecting GWs with forthcoming pulsar timing arrays (PTAs). A strong GW background, detectable at a level of 10-100ns timing precision, is a robust predictions of all the models. I will also discuss the prospects of resolving individual binaries, along with the issues of parameter estimation and search of potential electromagnetic counterparts.Speaker: Dr alberto sesana (Albert Einstein Institute, Golm)
-
72
Ultra-high dynamic range WSRT 1.4 GHz polarization observations of the Perseus clusterWe will present recent WSRT 21cm continuum observations of both discrete and diffuse sources of polarized emission seen in and towards the Perseus cluster of galaxies. The calibration of the data was done using Newstar and used both peeling, internal polarization leakage calibration and closure error correction. All this had to be done with sub-MHz frequency resolution to combat frequency structure in the telescope primary beam. The image dynamic range, on-axis and off-axis, exceeds 10^6 and almost noise limited imaging at 10 microJy levels per beam is achieved. Faraday spectra of background sources seen through the (periphery of the) cluster reveal unusually high RM, probably indicating ordered large-scale cluster magnetic fields and possibly the presence of a significant gaseous component in the Warm Intergalactic Medium. The diffuse Galactic polarized foreground is going to be a rich source of information, as well as a significant contaminant for background source studies, in SKA 1.4 GHz work at 15" and higher resolution.Speaker: Prof. Ger de Bruyn (ASTRON)
-
69
- 73
