Jodrell Bank to remain at the forefront of international astronomy
5th December 2001
UK astronomers are poised for a new era of discovery with the development of e-MERLIN, the world's most powerful radio telescope. This ambitious project will use new technology to connect antennas across the UK, creating the largest and most sensitive linked network in the world.
The 217km MERLIN radio telescope array, run by The University of Manchester's Jodrell Bank Observatory, is to be given a £7.8m upgrade. This has been made possible by the agreement, announced today, of the Particle Physics and Astronomy Research Council (PPARC) to continue funding MERLIN operations, so assuring the future of Jodrell Bank.
Professor Andrew Lyne, Director of the Jodrell Bank Observatory, welcomed the PPARC announcement:
"The enhancement to MERLIN will give UK astronomers access to one of the world's major astronomical research instruments. This development reflects the proven technical excellence of the University staff and their world-leading research programmes."
Dr. Philip Diamond, Director of the MERLIN/VLBI National Facility added:
"In combination with the newly resurfaced 76m Lovell telescope, the upgrade will give a 30-fold increase in sensitivity. This will enable the enhanced instrument, called e-MERLIN, to probe far deeper into the Universe, achieving in one day what would currently take three years of continuous observation."
The upgrade is to be funded by the North West Development Agency (NWDA) and a consortium of three universities - Manchester, UMIST and Cambridge. The NWDA have agreed in principle to a contribution of up to £2.5 million, and its Chief Executive, Mike Shields, welcomed today's news:
"I am delighted that the NWDA's funding contribution will help to secure the future of Jodrell Bank - a longstanding symbol of scientific endeavour in the North West. This package will not just maintain Jodrell Bank's position at the leading edge of world astronomy, but will also help to maintain the region's reputation for excellence in the future."
MERLIN is the UK's national radio-imaging facility and the only world-class astronomical facility based solely in the UK. No other radio facility in the world can routinely match the resolution of the Hubble Space Telescope. The completion of the new instrument in 2007 will help keep the UK at the forefront of astronomical research for years to come.
Radio-astronomy is crucial to the understanding of our Universe because radio waves penetrate the clouds of dust and gas that hamper observations at other frequencies. e-MERLIN will have unprecedented sensitivity and an imaging capability equivalent to viewing a 1p piece at a distance of 50 miles. It will thus open up new areas of science, particularly in fields such as extragalactic astronomy and cosmology, star formation across the Universe and studies of the extreme conditions around black holes.
The current MERLIN telescope is made up of seven radio-antennas sited around the UK. Much of the increase in sensitivity created by the upgrade will be due to the introduction of optical fibre connections between the antennas. This will allow a far greater proportion of the radio waves actually collected by the individual antennas to be brought back to Jodrell Bank than by the existing microwave radio links.
Dr. Diamond thanked Sir Martin Harris, Vice-Chancellor of the University of Manchester, for playing such a crucial role in putting together the capital funding package. He warmly welcomed the various partners involved in the project and also wished to thank the Cheshire County Council, North West Members of Parliament, and local Councillors for their great support, without which the project may well not have come to fruition.
Professor Tom Millar, Head of UMIST's Astrophysics Group said:
"My colleagues and I are very pleased to be part of this exciting development and look forward to using e-MERLIN to advance significantly our research on star formation and the late stages of stellar evolution."
Richard Hills, Professor of Radio Astronomy at Cambridge, said:
"This is very good news for the future of UK Radio Astronomy. One of the MERLIN antennas is located here and we are delighted to be playing a part in the project. We are very much looking forward to using the enhanced facility."
End of release.
Related images, contact details, background information and links to further information are given below.
|Location of the MERLIN telescopes||Location and photographs of the MERLIN telescopes||The 76m Lovell Telescope at Jodrell Bank||The 32m Telescope at Cambridge|
Jodrell Bank Observatory:
Dr Phil Diamond. Director, MERLIN/VLBI National Facility at Jodrell Bank Observatory.
Phone: +44-(0)1477 572625
Mobile: 0776 970 6872
Professor Andrew Lyne. Director, Jodrell Bank Observatory.
Phone: +44-(0)1477 572640
Dr Tom Muxlow. MERLIN operations team.
Phone: +44-(0)1477 572609
Dr Simon Garrington. MERLIN operations team.
Phone: +44-(0)1477 572607
The University of Manchester:
Mr Andy Swain. Information Officer
Phone: +44-(0)161 275 2018
Northwest Development Agency:
Ms Emma Degg
Phone: +44-(0)1925 400295
The University of Manchester Institute of Science and Technology:
Professor Tom Millar. Professor of Astrophysics
Professor Richard Hills. Professor of Radio Astronomy
Phone: +44-(0) 1223 337300
The home of the MERLIN network is the Jodrell Bank Observatory which is part of the Department of Physics and Astronomy of the University of Manchester. The MERLIN/VLBI National facility based in the observatory is operated by the University on behalf of the Particle Physics and Astronomy Research Council (PPARC).
MERLIN, developed 25 years ago from the pioneering experiments in long-baseline interferometry at Jodrell Bank, was designed to provide sub-arcsecond resolution at centimetre radio wavelengths. This was primarily to study in more detail the radio galaxies and quasars imaged by the Cambridge aperture synthesis arrays. Surpassing its original goals, both technically and astronomically, it was immediately recognised as a world-class instrument and many of its initial publications appeared in Nature. A major upgrade in 1990, in which the resolution was increased by nearly a factor of 2 and the sensitivity by almost an order of magnitude, ensured that MERLIN was transformed into a general-purpose instrument capable of attacking a wider range of astrophysical problems. Thus, it has remained a world-class astronomical facility; the only one entirely based within the UK. With its unique sub-arcsecond resolution matching that of the Hubble Space Telescope (HST), it has been identified as one of the leading strengths of UK astronomy, having an extensive user-base from 27 universities and other research establishments throughout the country.
In order to study the physics of astronomical objects, it is accepted that observations of similar resolution and sensitivity across the electromagnetic spectrum are required. However, it had become clear over the past few years that the sensitivity available at radio wavelengths was beginning to lag behind that available in other wavebands. Thus, radio facilities needed to be upgraded to make them comparable with and complementary to the new observational facilities in other regions of the electromagnetic spectrum. Thus the timely increase in the sensitivity of MERLIN will complement the upgrades of major radio astronomical facilities elsewhere in the world such as that of the 36 km Very Large Array (VLA) in New Mexico which has just been funded and will become the EVLA.
Image quality and resolution lie at the heart of MERLIN's success. Maintaining its resolution and vastly increasing its sensitivity, will enable e-MERLIN to carry out unique science. e-MERLIN will image in detail objects that can now only be glimpsed in the deepest observations and detect objects previously unseen at radio wavelengths with unprecedented resolution. It will provide radio images that complement those from the new generation of optical and sub-mm telescopes as well as probing regimes of the Universe not visible at other wavelengths. e-MERLIN will continue to bridge the resolution gap between the European and American very long baseline arrays (termed VLBI) and instruments such as the VLA. (Three of the Jodrell Bank telescopes take part in the European VLBI Network, the EVN. ) Many of the key problems being attacked by UK astronomers require radio observations at a sensitivity level that will be provided by e-MERLIN and with matched resolution to the HST. However, history shows that when any telescope makes a leap of more than an order of magnitude in sensitivity, it is the discoveries that could not have been predicted which turn out to have the greatest impact. For example, it was never anticipated beforehand that MERLIN would have such a significant impact on studies of the Hubble Deep Field.
One of the great achievements of radio astronomy over the past two decades has been the close cooperation between the VLA and MERLIN. Data from the two arrays have often been combined to produce high-quality, high-sensitivity images of a great variety of astronomical objects. It turns out that the data combination is a non-linear process in that the resulting images are far superior to what one might expect from a simple combination of the individual images from the two instruments. This is because of the additional constraints which results from a combination of the pre-processed data. The implementation of e-MERLIN will continue this partnership with the enhanced EVLA. With the Lovell telescope included in MERLIN, the upgraded instruments will have similar sensitivities at their principal observing frequencies, but when e-MERLIN data is combined with that from the EVLA the resultant images will have six times the resolution achievable by the VLA alone. e-MERLIN will thus enable the creation of one of most significant tools with which to probe the Universe.
The MERLIN Antennas.
There are 7 antennas in MERLIN. Two, the 76m Lovell Telescope and the 25m Mk II telescope are located at Jodrell Bank, some 20 miles south of Manchester in the Cheshire countryside. When incorporated into the array, the Lovell Telescope doubles the effective collecting area and so doubles MERLIN's sensitivity. Prior to the extensive upgrade which will be completed in the summer of 2002, the Lovell Telescope could only be used at the lower MERLIN operating frequencies, but from next year it will be able to be used at the key operating frequency of 5 GHz and thus give a sensitivity boost to MERLIN well before the commissioning of e-MERLIN later in the decade.
The oldest antenna in the array is located at Defford, near Great Malvern, 127 km south from Jodrell Bank. The wire mesh surface of the dish only allows observations up to 5 GHz, and ideally it would be replaced by a more modern antenna capable of operation up to 22 GHz. This part of the original e-MERLIN proposal has had to be dropped for the time being due to financial constraints.
There are three identical 25m antennas at Pickmere, near Northwich in Cheshire, Darnhall, south of Winsford in Cheshire and Knockin, near Oswestry in Shropshire. These are of similar design to those incorporated into the Very Large Array in New Mexico and can be used over the full range of MERLIN operating frequencies.
The most recent MERLIN antenna is the 32m at Cambridge. Completed in 1991, it formed a major part of the first upgrade to MERLIN and, by increasing the overall size of the array to 217km, doubled its resolution making it comparable to that of the Hubble Space Telescope.
The operational efficiency of the MERLIN array had been improved in the last few years by the implementation of "frequency flexibility". All MERLIN telescopes apart from the Lovell now have an array of receivers located close to the focus of the telescope which can be moved to the focal point by remote control. Changes between observations at different frequencies can thus be made with great ease. This, for example, allows observations at the highest frequencies, where weather conditions can effect the results, to be scheduled at short notice when conditions are optimum.
Linking the antennas into the MERLIN array.
Currently the signals from the MERLIN outstations are brought back to Jodrell Bank for analysis using microwave radio links. Their performance was substantially increased in the earlier MERLIN upgrade, but is still limited to returning 30 MHz of bandwidth to Jodrell Bank. This is the restriction that effectively limits the current performance of MERLIN. Most of the signal received by the telescopes has to be discarded prior to transmission due to the limited capacity of the links. The replacement of these links with those using optical fibres removes this limitation. It is the greatly increased data bandwidth that will provide the major part of the massive sensitivity increase of e-MERLIN.
Development of the required optical fibre technology for e-MERLIN is being carried out by Jodrell Bank engineers and will use bit rates of 30 Gigabits/second. This same technology will also be used for the future joint European and USA project, ALMA - the Atacama Large Millimetre Array. ALMA is to be located at a height of 16,400 ft in the Atacama desert in Chile and optical fibres will link the 64 or more antennas in the array with the central receiver laboratory. Similar data transmission systems will be used in future radio telescope projects such as the "Square Kilometre Array", so in this respect, e-MERLIN will act as a prototype system for these future developments.
Combining the data - the e-MERLIN Correlator.
The massive increase in the data returned from the telescopes of the e-MERLIN array will require a very powerful system to carry out the required data processing in real time. With each antenna returning over 30 Gigabits of data per second to Jodrell Bank, half a million times faster than the average home modem, the continuous data rate analysed by the new correlator will exceed 200 Gigabits per second! The required data throughput is greater than even the fastest general purpose processors can achieve, so a special purpose "correlator" will be required. The costs of designing and implementing such a system are great and would not be affordable with e-MERLIN funding alone. The design and construction of the correlator will thus also be an international project with Jodrell Bank engineers working with those from Canada and the USA in its design and implementation. It is hoped that the correlator will be developed in Canada funded by the National Research Council of Canada, the National Science Foundation of the USA and ourselves. Versions of the correlator will be then be constructed both for e-MERLIN and the EVLA project referred to above.
For examples of the astronomical research carried out with the MERLIN telescope array see the Astronomy Section of the MERLIN/VLBI National Facility Biennial Report 1999/2000.
For more details on the e-MERLIN project see the e-MERLIN summary page.