From: <Tasso.Tzioumis_at_email.protected>
Date: Thu, 1 Sep 2005 01:40:27 +1000

Congratulations Sergei and all the team.

A great show! I am sure fringes to NZ are not far behind.

Cheers
Tasso

On 31/08/2005, at 12:30 PM, Chris Phillips wrote:

>Hi Guys,
>
>This message is from Sergei. It bounced for some reason.
>
>Cheers
>Chris
>
>-----------------------------------------------
>
>Dear All,
>
>Let me inform you about the progress towards New Zealand radio
>astronomy and Trans-Tasman VLBI. The VLBI test was conducted between
>Hobart and ATCA last week . This is the second time when the
>University of Tasmania generously provides us with the opportunity to
>test the whole NZ system at Mt Pleasant Observatory.
>
>In April 2005 the NZ system was tested in Hobart for the first time.
>The multibeam correlator was used to cross-correlate between the 14m
>and 26m radio telescopes on a short baseline of about 100m. One of the
>telescopes (14m) was equipped with the principal components of the NZ
>system (feed, L-band receiver, sampler, etc.). We got fringes for a
>number of radio sources, including 5Jy QSO. However, the first test
>wasn't truly VLBI (just 100m baseline), besides neither clock nor data
>recorder were tested properly.
>
>Since April 2005 we (NZ and Australian e-VLBI team) have been trying
>to do Trans-Tasman VLBI (very long baseline interferometry). We had
>two VLBI sessions between NZ 6m Brent Addis radio telescope (BART-6)
>and Australian big radio telescopes in May and July. No fringes were
>found. All was checked, double-checked and analyzed, and we came to
>the conclusion that the sensitivity of the 6m RT we used in NZ was too
>low.
>
>Now Steven Tingay suggested to combine the NZ system with the 14m
>antenna again, this time for the VLBI test with Australian Telescope
>Compact Array (ATCA). Last week for the second time we brought all our
>system from NZ to Tasmania. This time the 14m dish was fully equipped
>with the NZ equipment (including the data recorder, Rubidium clock and
>even GPS). This time the baseline was very long.
>
>This VLBI test was very successful. A 5 Jy source (0537-441) gave a
>very strong fringe (14 sigma with just 1 s integration time). Data was
>cross-correlated with the software correlator developed in Swinburne.
>The test has proved that the NZ system does work in the conditions of
>real VLBI. It is clear now that the 6m RT is marginal in terms of
>sensitivity. Now, with much better understanding of the parameters of
>the NZ system (such as instrumental time delay, system temperature,
>etc.) we are pretty confident that we will get fringes in the next
>Trans-Tasman test, provided we use longer integration time. It is also
>possible that fringes can be found in the data stored from out
>previous VLBI sessions.
>
>Since we started 6 months ago, we learned a lot about the system and
>the telescope we use. Some innovative approaches were developed. For
>example, it was demonstrated that two inexpensive Rubidium clocks
>combined and disciplined with GPS can serve as a reliable VLBI time
>standard (dt/t ~ 10E-12). Due to great help and support from our
>Australian colleagues and friends we have evolved to the stage when
>single-dish radio astronomy became fact in NZ, and Trans-Tasman VLBI
>is just the matter of greater collecting area. There is no doubt that
>NZ will soon become a part of Australian and international VLBI
>network.
>
>We thank John Dickey and Brian Boyle for providing Director's time
>and full support in radio observatories of the University of Tasmania
>and ATNF. Many thanks to Peter McCulloch and Simon Ellingsen for their
>help, as well as to Brett Reid and Eric in the observatory for
>round-the-clock support. Massive thankyou to Steven Tingay, the
>initiator and the champion of the Trans-Tasman VLBI development. It
>was a great pleasure to meet Adam Deller, who turned software
>correlation process into art and great fun. We appreciate their help
>and hard work. (One of our working days in Hobart lasted 31 hours
>non-stop!) Special thanks to Brent Addis, talented New Zealander, who
>built fully steerable 6m radio telescope in his backyard, and to Tim
>Natusch, brilliant NZ engineer and devoted radio astronomer, for his
>great commitment and expertise.
>
>Sergei
>
>P.S. When in Hobart, we tried interferometry for OH maser
>330.878-0.367 with strong (S~300 Jy) but narrow (5-7 km/s) emission
>line in 1665 MHZ. We could see strong OH line in the spectrum received
>on the 14m with NZ system (first NZ radio spectroscopy?).
>Surprisingly, we got strong fringe between Hobart and ATCA. Adam
>promptly found the explanation: there is a 8 Jy HII region associated
>with this maser source.
>
>P.P.S. One of our experiments in Hobart we called "Challenge". We
>wanted to find the weakest source observable with 14m+26m
>interferometer. It was 1.5 Jy QSO (2322-411), which gave us 5 sigma
>fringe with 10 s integration, and 7 sigma fringe with 20 sec
>integration time. No fringes were found from 1.0 Jy thermal source
>J1514-4748.
>
>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
>
>>>>Steven Tingay <stingay_at_astro.<!--nospam-->swin.edu.au> 22/04/2005 8:10:29 p.m.
>>>>
>>>>
>Dear All,
>
>Sergei Gulyaev and Tim Natusch from the Auckland University of
>Technology
>have been at the Mt Pleasant Observatory of the University of
>Tasmania for
>the last few days, testing their equipment for the upcoming
>Trans-Tasman
>VLBI tests. They have been assisted by Brett Reid, Eric Baynes, Simon
>
>Ellingsen, Guiseppe Cimo, Peter McCulloch, and myself.
>
>I thought that I would bring you up to date with our progress toward
>the
>goal of first Trans-Tasman VLBI, since we have made some very
>significant
>and encouraging first steps.
>
>Sergei and Tim brought with them the equipment they have built:
>
>* 1.6 GHz RF system (feed, LNA, Rubidium, downconversion, receiver);
>* sampler and digitiser;
>* disk-based recording PC.
>
>We mounted the 1.6 GHz feed on the 14 m antenna at Mt Pleasant and
>connected the AUT RF system. We tested coherence of the RF system and
>
>tested the Rubidium clock against the Mt Pleasant maser.
>
>At this point we used the AUT equipment to detect its first
>astronomical
>source, the Crab nebula in Taurus. From this measurement we derived a
>
>system equivalent flux density of approximately 15,000 Jy, allowing
>us to
>calculate the likely system temperature of the AUT system (~300 K).
>This
>is an important number for estimating the baseline sensitivity that
>we can
>expect from our first Trans-Tasman VLBI, and therefore the sources we
>need
>to observe.
>
>We then undertook the first VLBI observation using the AUT equipment,
>
>albeit on quite a short baseline. We ran the 14m antenna using the
>AUT RF
>system and Rubidium clock. We ran the University of Tasmania 26m
>antenna
>(~100m away) using the normal LBA VLBI setup. We used both IF inputs
>of
>the LBA DAS to feed the multi-beam correlator and form the
>auto-correlations for the 14m and 26m, as well as the
>cross-correlation of
>the 14m and 26m signals. We found very strong fringes to the Crab
>nebula
>(~few hundred Jy) and strong fringes to 3c161 (~10 Jy) on that 100m
>baseline using 5 second integration times. Next, we will test the
>system
>on the weaker sources (~5 Jy) that we will have to use for the first
>
>Trans-Tasman VLBI tests.
>
>We also recorded some data for correlation in software on the
>Swinburne
>supercomputer, for more detailed analysis in the coming weeks.
>
>These tests are highly significant as we have verified the operation
>of
>the AUT equipment, showing that the system sensitivity, time-keeping,
>and
>recording hardware are all up to scratch, giving us a degree of
>confidence
>that the first true VLBI tests, hopefully to be performed in May,
>will be
>successful. We have removed a number of areas of uncertainty in the
>AUT
>system.
>
>I'd like to give a massive thankyou to Eric and Brett in Hobart, as
>well
>as Giuseppe and Simon, and of course Sergei and Tim, for making these
>
>tests successful. We are all very excited about taking the next step
>on
>the way to Trans-Tasman VLBI.
>
>And, congratulations to Tim and Sergei!
>
>Cheers, Steven
>
>##=====================================================##
>Dr Steven Tingay stingay_at_astro.<!--nospam-->swin.edu.au
>Swinburne SKA Project Leader
>Senior Lecturer
>
>Centre for Astrophysics and Supercomputing
>Swinburne University of Technology
>Mail No H39
>P.O. Box 218, Hawthorn, Vic. 3122, Australia
>
>ph: +61 3 9214 8758
>fax: +61 3 9214 8797
>
>http://astronomy.swin.edu.au/ska
>##=====================================================##
>
Received on 2005-09-01 01:40:54