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ATNF News
Issue No. 66, April 2009 ISSN 1323-6326


See Compact Array Broadband Backend (C ABB) ar ticle on page 6. Left to right: C ABB Project Leader Dr Warwick Wilson, CSIRO Chief Executive Officer Megan Clar k and ATNF Acting Director Dr Lewis Ball, with a C ABB signal processing board in front of two antennas of the Australia Telescope Compact Array. Photo: Paul Mathews Photographics

Removing the "spaghetti" of ribbon cable that fed the old correlator, from left to right, Matt Shields (obscured), Brett Hiscock, Scott Munting, Mar k Leach, and Peter Mir tschin. Photo: CSIRO

Cover page images
C ABB Project--team photo. Back row, left to right: Warwick Wilson (Project Leader), Paul Rober ts, Grant Hampson, Peter Axtens, Yoon Chung. Middle row: Aaron Sander s, Dick Ferris (Project Engineer), Matt Shields, Mar k Leach (Project Manager). Front row: Troy Elton, Andrew Brown, Raji Chekkala, Evan Davis. Other contributor s (not in photo): Scott Saunder s. (See ar ticle on page 6.) Photo: Tim Wheeler, April 2009 The Sunrise television crew prepare to broadcast live from the grounds of the CSIRO Par kes Obser vator y. Photo: Tim Ruckley, CSIRO Installation of a 300 ­ 900-MHz receiver on the Par kes 64-m radio telescope . (See ar ticle on page 28.) Photo: Maik Wolleben, CSIRO

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Contents
Editorial............................................................................................................................................................................. 3 From the Director...................................................................................................................................................... 4 Brian Boyle Takes up New Role as CSIRO SKA Director ................................................................... 5 Compact Array Broadband Backend .............................................................................................................. 6 Exchange Exper tise ................................................................................................................................................... 8 ATNF Distinguished Visitor s ................................................................................................................................. 9 ATNF Graduate Student Program ................................................................................................................... 9 Highlighting our Histor y: Potts Hill Field Station, 1948 ­ 1962 ........................................................ 10 Australian Square Kilometre Array Pathfinder (ASKAP) ..................................................................... 14 OCE Postdoctoral Fellowship Success ........................................................................................................... 17 Pulse@Par kes: A Month of Pulsar Obser ving with the ASKAP Test-bed Antenna ................ 18 Unraveling the Mysteries Surrounding the Life and Death of the Most Massive Star s ...... 20 S-PASS: the Polarised Southern Sky ................................................................................................................. 24 National Facility Operations ................................................................................................................................. 27 Time Assignment Information ............................................................................................................................. 31 ATNF Publications List ............................................................................................................................................. 32 ATNF Outreach .......................................................................................................................................................... 34

Editorial
In this issue, Phil Edwards reports on the tremendous achievements that have taken place with the Compact Array Broadband Backend (CABB) project. This is an upgrade that will keep the Australia Telescope Compact Array at the forefront of radio astronomy, providing observers with much improved bandwidth allowing for more sensitive observations. We also feature a number of articles which highlight the wide-ranging and insightful science being undertaken at ATNF facilities. Franz Bauer and collaborators report on SN1996cr, the strongest radio supernova ever discovered, while Ettore Carretti reports on the S-band Polarisation All Sky Survey (S-PASS), a project to map the diffuse polarised synchrotron emission of the entire southern sky. In other news, George Hobbs and collaborators discuss pulsar obser ving with the ASKAP test-bed antenna situated at Parkes, while a histor y of the research undertaken at Potts Hill Field Station is examined in a paper by Harr y Wendt, Wayne Orchiston and Bruce Slee. Finally, we provide an in-depth update on ASKAP activities including a special antenna report prepared by Ross Forsyth, together with information on the SKA Forum held in Cape Town, as well as information on continuing ASKAP industr y engagement. As this issue was being prepared, we were saddened to hear of the death of John Masterson on 9 April 2009. John was an esteemed and highly respected photographer with the CSIRO Division of Radiophysics. For 40 years he made a huge contribution to a magnificent photographic archive that records the events, facilities and people that make up the histor y of CSIRO Radiophysics and the ATNF since the earliest days. Examples of his superb photography can be seen around the Marsfield site, ATNF Obser vatories and in many publications. An obituar y and examples of his work will be available in the next edition of ATNF News . If you would like to contribute to later editions of the ATNF News, please contact the newsletter team. Tony Crawshaw and Joanne Houldswor th The ATNF Newsletter Production Team (newsletter@atnf.csiro.au)

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From the Director
Lewis Ball ATNF Acting Director

This newsletter details a range of achievements by a great team of people engaged in radio astronomy activities. It is increasingly impor tant to recognise that the makeup of that team extends well beyond the staff within the Australia Telescope National Facility (ATNF) and the astronomer s who use our telescopes.
The biggest news at this time for users of the ATNF telescopes is the start of scientific operations of the Compact Array Broadband Backend, or CABB, on 22 April 2009. The system is described in articles within this newsletter. I'd like to acknowledge here the contributions of the team that have made this project possible. Warwick Wilson has led the CABB project from its inception and Warwick and the rest of the ATNF's back end engineering group have worked tirelessly on this very challenging project for the last seven years. The expertise of the group was acknowledged as being world class by the independent, international panel that conducted the ATNF Science Review in 2007. In their overview, the Science Review panel stated: "In the area of digital signal processing, the ATNF developed the first digital frequency conversion system for Very Long Baseline Interferometry (VLBI) and their experiments in electronicVLBI (e- VLBI) have achieved very competitive bandwidths. The advanced design and short development time of the new Compact Array Broadband Backend, which is enabled by utilising the latest Field Programmable Gate Arrays (FPGAs), is comparable with the best at other observatories. The sampling speeds and resolution of the digitisers now being tested for CABB are amongst the highest achieved at any observatory. The ATNF was the first obser vator y to use digital data transmission of radio astronomical data on optical fibres and their use of this technology for CABB is state-of-the-art." Significant funding was received from the Major National Research Facilities grant from the 2001 round on the basis that the technology underlying CABB was on the development path towards the realisation of the Square Kilimetre Array (SKA). As the focus shifts from building CABB to using and operating it, the staff of the back end group will shift their efforts further towards the development of the beamformer, correlator and data transport systems for the Australian SKA Pathfinder (ASKAP), while the software and firmware gurus (Warwick Wilson and Dick Ferris) continue to work on providing different modes of operation of CABB. Operations and astrophysics staff are now in the front line of ensuring that astronomers can make the best use of the new system, and I am sure that in years to come it will result in science that we haven't predicted. In another significant change, CSIRO recently created the new position of CSIRO SKA Director and appointed Brian Boyle to that role. Having worked closely with Brian as his Deputy since 2005 I'd like to take this opportunity to personally thank him for his outstanding efforts as ATNF Director.

Brian deser ves specific acknowledgement for his leading role in the development of the Decadal Plan for Australian Astronomy in 2005, and for the rapid firming of Australia's commitment to playing a leading role in the SKA. The resulting funding of A$51.7M from the Commonwealth Government to CSIRO to expand its plans for a new telescope in Western Australia to become the Australian SKA Pathfinder is one of the largest injections of funds into Australian astronomy. This will continue to have a profound impact on Australian astronomy in future decades. Brian's new role, in which he is seconded into the Department of Industr y, Innovation, Science and Research for 40% of his time, is further indication of Australia's and CSIRO's commitment to the strategic opportunities associated with radio astronomy over the decades to come. It is a privilege for me to fill the role of Acting Director of ATNF until CSIRO completes a competitive appointment process for a new Director. This is expected to occur by the end of 2009. In the role of ATNF Acting Director I continue to work very closely with Brian. I have responsibility for the ATNF Business Unit--essentially all the staff and equipment--and for the deliver y of the Operation of the National Facility telescopes, the astrophysics research activities, and the technical and engineering research and development (other than ASKAP). Brian is responsible for SKA-related activities including the deliver y of ASKAP as a working telescope. This newsletter encapsulates the past, present and future through the historical article on the Potts Hill

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Brian Boyle Takes up New Role as CSIRO SKA Director
Tony Crawshaw (ATNF)

Field Station; the excellent science of the present outlined in the science highlights and the start of CABB operations; and the potential and excitement of the future through the training and inspiration of students, the development of ASKAP, and the promise of the SKA. All these elements are important for the continued success of the ATNF, including the sometimes difficult and confronting need for change. The tremendous response from the astronomy community around the world to the call for Expressions of Interest in the major survey science projects to be undertaken by ASKAP has marked a dramatic turning point for the ATNF. The fact that 354 astronomers from around the world got together to submit Expressions of Interest for surveys that won't start for another three years or more is a very positive indicator of the potential of ASKAP to deliver transformational science. The efforts of the survey teams that are selected following the assessment of the more detailed proposals currently being prepared will be essential for the success of the ASKAP telescope, and those efforts are greatly appreciated by CSIRO. One of the most rewarding parts of my role is seeing the results of the recruitment of new staff. Over the past few months I have been reminded again and again by new members of the ATNF that this is a great place to work and that there is a tremendous sense of excitement. Two of our new starters, Ettore Caretti and Jamie Stevens who have taken on the roles of Senior Systems Scientists at Parkes and Narrabri respectively,

On 9 Febr uar y 2009, Dr Brian Boyle stepped down as the Director of ATNF to take up a new role as CSIRO SKA Director. The role was created to strengthen Australia's bid for the international Square Kilometre Array (SKA) radio telescope mega-project.
In his new role Dr Boyle is now focused on strategic international SKA policy issues, working closely with the Department of Innovation, Industry, Science and Research. As well as taking on a joint leadership role with senior Departmental officials in helping to develop and implement Australia's SKA strategy, he continues to be responsible for the deliver y of the Australian SKA Pathfinder Telescope, ASKAP, which is being developed by CSIRO. The new role has already allowed Dr Boyle to assume the chairmanship of the Australian SKA Co-ordinating Committee (ASCC), the intergovernmental peak body for the oversight of Australia's SKA strategy and policy. In that capacity Dr Boyle has helped to revise the working group structure for the ASCC, targeting the demonstration of SKA-readiness to the international community as a key goal over the coming two-three years. Dr Boyle is also committed to broadening and enhancing the engagement of the ASCC with the community. As part of this approach, Prof Br yan Gaensler has been appointed to the Chair of the ASCC Science and Technology Advisor y Committee. Through the ASCC, Dr Boyle is also currently working with officials from the New Zealand Government to secure New Zealand's formal participation in Australia's SKA program. Dr Lewis Ball (previous ATNF Deputy Director) is acting as ATNF Director until a successor is appointed.

will become ver y well known to our astronomy users in the coming months. I'd like to acknowledge the enthusiasm of all our new staff members who are too numerous to mention here but who all have important roles to play and are greatly valued. Finally, I'm sure many will be interested in the fact that CSIRO's invention of the techniques that underpin the wireless communications, now so common for connections between computers and

other electronics devices, has its roots in radio astronomy. Two keystones were John O'Sullivan's push to develop FFT capable chips to use in searches for transient radio emission from predicted collapsing black holes, and his work in recognising that redundant spacing interferometr y could be used to cancel phase errors introduced in signal propagation. For more, see: www.csiro.au/science/wireless-LANs .html

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Compact Array Broadband Backend
Philip Edwards (ATNF)

The Australia Telescope Compact Array (ATC A) emerged recently from a six-week shutdown during which installation of the Compact Array Broadband Backend (C ABB) system hardware was completed. C ABB has increased the maximum bandwidth of the ATC A by a factor of 16, from 128 MHz to 2 GHz, improving the continuum sensitivity of the ATC A by at least a factor of four as well as providing a greatly enhanced spectral line performance, par ticular ly at the higher obser ving frequencies. The fr uition of the C ABB project will provide a great boost in the capabilities of the Compact Array and is a credit to the ATNF engineering group for the development and integration of the C ABB system with the existing array infrastr ucture. The fir st scheduled astronomical obser vations with C ABB occured on 22 April 2009, a day after CSIRO's new Chief Executive Officer, Megan Clar k, visited the Obser vator y and inspected the freshly upgraded array.
The CABB project commenced in January 2002, and had at its core a new digital signal processing system based on a novel Polyphase Digital Filter Bank (DFB) structure developed at ATNF. Key milestones on the path to completion of CABB have included provision of the MOPS spectrometer for the Mopra telescope in 2006, and the Pulsar Digital Filterbanks at Parkes. CABB has also provided a test-bed for ASKAP and future SKA technologies in its ability to provide wideband data sampling, transmission, and processing. CABB replaces the Compact Array's original signal processing and digital correlator systems. Those systems, at the time of their design and construction in the 1980s, were "stateof-the-art" and gave the Compact Array a keen competitive edge when it began operating in 1990. The CABB project has benefited from being led by Warwick Wilson who was the designer and project leader for the original correlator. Warwick, together with Mark Leach and Dick Ferris (Project Manager and Project Engineer respectively), have led a team that, for knowledge and experience in digital signal processing for radio astronomy, has few peers around the world. The success of CABB bodes well for the ATNF's future involvement in the construction of the SKA. Over the last year an interim CABB system has been progressively installed on the ATCA. The interim system, which ultimately provided a single 2-GHz bandwidth, with dual polarisations, for five of the six ATCA antennas, was able to be operated in parallel with the existing correlator system, allowing a valuable series of comparisons and cross-checks to be made. This capability vanished in the first week of the shutdown when the nine racks and (seemingly!) miles of ribbon cable of the old correlator were removed and the first of the three CABB racks installed in its place (See inside front cover). In concert with the signal transmission and processing hardware changes, modules to interface the current suite of receivers to the new system have been fabricated and installed. Currently the 12-mm, 7-mm, 3-mm and 3/6cm bands are available. Modules to enable obser ving with the 20-cm or 13-cm band are expected in late May. The great advance in the array's capabilities provided by CABB is, perhaps surprisingly, accompanied by a simplification of the equipment on the antennas. The frequency conversion of the radio-astronomical signals has been simplified and is at most a twostep process, rather than four ; the "fringe rotation" of the signals no longer happens in the antennas; and the analog-to-digital conversion of the signal now uses 9-bit sampling rather than 2-bit sampling, providing high dynamic range and tolerance to high levels of radio-frequency interference, an inevitable feature of wider bandwidth obser vations in the centimetre wavelength radio-bands. An inherent property of the digital filterbank structure is its excellent isolation between channels, so that strong interference at one frequency does not leak into neighbouring

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frequency channels. The wider bandwidths and finer sampling result in an increase in data flow to the central correlator by a factor of 80, from 2 to 160 gigabits per second per antenna--a data rate of just under one terabit per second for the array! CABB will initially operate in a single observing mode, offering 2048 spectral channels across a 2-GHz bandwidth. Over the coming months the first of the "zoom modes", offering increased spectral resolution over selected portions of the 2-GHz band, will be implemented. To accommodate this progressive enhancement of observing capability, the six-month April 2009 observing semester for the ATCA has been split into two parts, with a 1-MHz spectral resolution offered for the first three months, to mid-July, and the first zoom modes offered for the latter part of the winter semester. The astronomical community's interest in CABB is apparent from the very high oversubscription rate for the first three months. ATNF Assistant Director : Operations, Dave McConnell noted "The ATNF has always benefited from having astronomical and engineering staff co-located and in constant communication about what is both useful and technically possible in radio astronomy: in the ATNF `the science drives the technology' and `technology drives the science' have both been true statements, and CABB is the latest product of such a relationship." The ATCA shutdown for the CABB installation and commissioning was

scheduled to take six weeks from the beginning of March, but benefited from gaining advance access to antenna CA06, which was made available during the Long Baseline Array block at the end of Februar y. This enabled a head-start to be made on a number of antenna-related changes, and allowed the procedures also needed on other antennas to be fine-tuned ahead of time. While the extended array downtime was primarily for CABB, a number of other maintenance tasks were also carried out: twelve antenna drive motors (each antenna has four drive motors, two for elevation and two for azimuth) were rewired and fitted with connectors to allow quick and safe disconnection and reconnection during maintenance or changeovers; two 20/13-cm receivers were warmed in readiness to change receiver packages for those with new ortho-mode transducers (improving the 13-cm polarisation capabilities); and a variety of other preventative maintenance tasks were also undertaken. The new CABB system has also required significant changes to the array control and monitoring software, which has taken place in parallel with the hardware changes. In addition, the ATCA data analysis package, miriad, has required revision and extensions to enable (the significantly larger) CABB data files to be processed. The ATC A Users Guide is also being given a complete overhaul to bring it into the CABB era. It goes without saying that the shutdown was a period of great

A new C ABB antenna rack being lifted into an antenna for fitting. Photo: Brett Hiscock activity, with a steady stream of visitors from ATNF Headquarters in Marsfield, and obser vator y staff, working long hours to ensure the installation and commissioning was kept to schedule. Recent studies of the scientific impact of radio-telescopes have shown the ATCA and Parkes jostle for second and third place, and CABB and its offspring DFBs at Parkes will ensure these telescopes continue to enjoy pre-eminence well into the future.

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Exchange Exper tise
Graeme Carrad (ATNF)

The Front End Group benefitted tremendously during the period October 2008 to Januar y 2009 when the Italian National Institute for Astrophysics (INAF) allowed one of its engineer s to donate his ser vices to the ATNF.
Alessandro Navarrini proved his worth in developing a design for a new C-band amplifier that, if successful, has the potential to relieve the dearth of spare amplifiers needed for the Compact Array. Alessandro is based at the Cagliari Astronomy Observatory

(OAC) and is involved in the design and construction of the various receivers for the 64-m diameter Sardinia Radio Telescope (SRT.) His amplifier design uses "off the shelf " components and electromagnetic simulation of the device performance is encouraging. In addition to his electronic design efforts, Alessandro put in many dedicated hours to generate mechanical drawings of the amplifier body and circuit board. The amplifier is currently being fabricated. It wasn't all work however and he was introduced to the Australian bush

through bushwalks and a canyoning trip. His favourite pastime of snorkelling was catered for with an introduction to the fish at Shelly Beach near Manly. Having only had exposure to small fish near Sardinia, the size of the blue groper that is resident in the waters there seemed to give him cause for caution and something to remember. The benefits of the exchange of expertise are unquestionable and may lead to further exchanges and strong links between the two institutions in the years to come.

Alessandro takes time out from wor k to enjoy an Australian bushwalk and canyoning trip. Photos: Cour tesy of Alessandro Navarrini.

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ATNF Distinguished Visitor s
Rober t Braun (ATNF)

ATNF Graduate Student Program
Baerbel Koribalski (ATNF)

Over the past months we have enjoyed working visits from Franz Bauer (Columbia University), Marta Burgay (Cagliari), Martin Cohen (University of California Berkeley) and Ingrid Stairs (University of British Coumbia).Current visitors include Leo Blitz (University of California Berkeley) and Phil Kronberg (Los Alomos National Laboratory/ University of Toronto). Upcoming visitors we expect include Martin Cohen (University of California Berkeley), Rick Jenet (University of Texas Brownsville) and D J Saikia (Tata Institut of Fundamental Research). The Distinguished Visitors Program remains a very productive means of enabling collaborative research projects with local staff, adding substantially to the vitality of the ATNF research environment. Visits can be organised for periods ranging from only a few weeks up to one year. For more information please see www.atnf.csiro.au/people/ distinguished_visitors.html. Prospective visitors should contact the local staff member with the most similar interests.

We welcome the following students into the ATNF co-super vision program:
· Luke Hindson (University of Hertfordshire)--Wide-field molecular imaging of triggered star formation with super visors Dr Mark Thompson (University of Hertfordshire) and Dr James Urquhart (ATNF); Lina Levin (University of Swinburne)--The High Time Resolution Universe with super visors Dr Matthew Bailes (University of Swinburne), Dr Simon Johnston (ATNF), Dr Michael Kramer (Max-Planck-Institut fЭr Radioastronomie, Bonn, Germany) and Dr Willem van Straten (University of Swinburne); Anita Titmarsh (University of Tasmania)--Investigating the earliest stages of massive star formation with super visors Dr Simon Ellingsen (University of Tasmania) and Dr Kate Brooks (ATNF).

Congratulations to:
· Marcella Massardi on the successful submission of her International School for Advanced Studies of Trieste PhD thesis on The extragalactic sources at mm wavelengths and their role as CMB foregrounds; Adam Deller on the successful submission of his University of Swinburne PhD thesis on Precision VLBI astrometr y: Instrumentation, algorithms and pulsar parallax determination; and Emil Lenc on the successful submission of his University of Swinburne PhD thesis on Studies of Radio Galaxies and Starburst Galaxies using Wide-field, High Spatial Resolution Radio Imaging.

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Dr Marcella Massardi is now a postdoc at the INAF-Osser vatorio Astronomico di Padova in Italy. Dr Adam Deller has started a Jansky Fellowship at the National Radio Astronomy Obser vator y Socorro, USA, and Dr Emil Lenc is an OCE Postdoctoral Fellow at the ATNF.

Clockwise from left: Luke Hindson, Lina Levin, Katherine Newton-McGee, Joris Verbiest, and Adam Deller and Emil Lenc. Not shown: Anita Titmar sh, Marcella Massardi and Nadia Lo. Photos: Cour tesy of students.

The following students recently submitted their PhD Thesis:
· Nadia Lo (University of NSW)-- A Multi-molecular Line Study of an Entire Giant Molecular Cloud; Katherine Newton-McGee (University of Sydney)--Radio Polarimetr y as a Probe of Interstellar Magnetism; Joris Verbiest (University of Swinburne)--Long-Term Timing of Millisecond Pulsars and Gravitational Wave Detection. Joris is now at the University of West Virginia.

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Well done !
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Highlighting our Histor y: Potts Hill Field Station, 1948 ­ 1962
Harr y Wendt, Wayne Orchiston (JCU Centre for Astronomy) and Br uce Slee (ATNF & JCU Centre for Astronomy)

This paper provides a summar y1 of the research carried out at the Potts Hill field station during the seminal period of Australian radio astronomy prior to 1960. This was arguably the most exciting and innovative era in the development of Australian radio astronomy. It was the era before

"big science" projects emerged, a period when small-scale projects dominated and radio engineer s fir st entered the domain of the astronomer s. Most obser vations were carried out at a networ k of field stations maintained by the CSIRO's Division of Radiophysics

in or near Sydney.2 This was a unique period when--along with Britain--Australia achieved wor ld leader ship in the new field of radio astronomy. As Hanbur y Brown (1993) remar ked, "... golden ages in science are rare and should be recorded."

The Potts Hill field station was located in the western suburbs of Sydney, 16 km from the centre of Sydney and on vacant land adjacent to a major water-distribution reser voir (see Figure 1). The site was selected in 1948 after it was necessar y to find a new home for a 97-MHz sweptlobe interferometer which was being developed by Ross Trehearne and Alec Little. The building in which they were working at Bankstown aerodrome was sold and so a new location had to be found. At the same time Ruby Payne-Scott took over the project from Trehearne. Permission was kindly given by the Sydney Water Board to use the vacant land surrounding the Potts Hill No. 1 reser voir, and the Potts Hill radio astronomy field station came into being. Soon after Little and Payne-Scott had relocated to Potts Hill they were joined by W N ("Chris") Christiansen who had recently transferred from AWA Figure 1: A n aerial photograph of Potts Hill field station taken on 19 March 1954. The view is from the nor th looking south. The main par t of the field station is in the immediate foreground. The East-West solar grating array is on the southern bank of the reser voir and the Nor th-South array on the eastern bank. On the bottom left, three coal train carriages are visible. These were used to supply coal for the steam driven pumping station for the water supply reser voir. The main road visible on the left is Rookwood Road. Photo: (CSIRO Radiophysics Photographic Archive: B3253-1)

1 2

For a detailed discussion see Wendt, 2009. For an over view of the Field Stations see Orchiston and Slee, 2005.

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to Radiophysics and was also looking for a new site where he could conduct solar observations with a 4.9- в 5.5-m paraboloid that was originally installed as an experimental radar at Georges Heights during WWII (see Figure 2). Ten different types of radio telescope operated at Potts Hill during the 15-year life of the field station. Amongst these were several examples of world-first instruments. The Swept-Lobe Interferometer developed by Little and Payne-Scott (1951) used a method of continuously varying the phase of the local oscillator in the heterodyne receiver to sweep the aerial beam lobes at 25 times a second. This innovation removed the restriction of having to wait for the Earth's rotation to move the source through the lobe pattern in order to produce interference fringes. Not only could the SweptLobe Interferometer determine the position of a short duration burst accurate to two arc minutes at 97 MHz, it could also measure the polarisation of the source. This radio telescope was designed primarily to provide accurate positional measurements of short-duration solar bursts and was successfully used to track the motion of these through the corona for the first time. In fact, several of the bursts they measured would later turn out to be Type IVs, the only type of solar burst not discovered by an Australian group. The Swept-Lobe Interferometer could also be used as a traditional interferometer by by-passing the swept phase-changer. In this mode it was used by Bernard Mills and A B Thomas in the evenings when