Number 12
September 2005
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European VLBI Network
Newsletter Number 12 September 2005 |
| EVN Homepage | Publications | Meetings | User Support | Proposals | JIVE Homepage | Newsletter Archive |
| Contents | |
| Announcements |
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Observing proposals are invited for the EVN, a VLBI network of radio
telescopes spread throughout Europe and beyond, operated by an
international Consortium of institutes (
http://www.evlbi.org/).
The EVN is open to all astronomers. Use of the Network by astronomers
not specialised in the VLBI technique is encouraged.
The Joint Institute for VLBI in Europe (JIVE) can provide support and
advice on project preparation, scheduling, correlation and
analysis. See EVN User Support at http://www.jive.nl.
EVN Observing Sessions in 2006
| 2006 Session 1 | Feb 16 - Mar 09 |
18/21cm, 6cm (+MERLIN), 5cm (+MERLIN), 3.6cm |
| 2006 Session 2 | Jun 01 - Jun 20 | 30cm, 18/21cm, 6cm, +... |
| 2006 Session 3 | Oct 19 - Nov 09 | 18/21cm, 6cm, +... |
Proposals received by 1 October 2005 will be considered for scheduling in Session 1, 2006 or later. Finalisation of the planned observing wavelengths will depend on proposal pressure. Other wavelengths which may be scheduled in 2006 are: 90cm, 50cm, 1.3cm, 7mm.
Special
features for Sessions in 2006
-------------------------------------
* It is anticipated that MERLIN will be available in all sessions.
* Disk schedules (ignoring tape boundaries) now used for EVN-only
projects.
* Recording at 1 Gb/s (Mark 5A) available for projects which need it
(see http://www.mpifr-bonn.mpg.de/div/vlbicor/evn_tog/EVN_Mark_5_Status.html).
* 0.25s integrations available at EVN MkIV Data Processor at JIVE
for wide-field applications.
* EVN Data Analysis pipeline in operation. See http://www.evlbi.org/pipeline/user_expts.html.
Large projects
--------------
Most proposals request 12-48hrs observing time. The EVN Program
Committee (PC) also encourages larger projects (>48 hrs); these
will be subject to more detailed scrutiny, and the EVN PC may, in some
cases, attach conditions on the release of the data.
How to submit
-------------
Complete a coversheet and attach a scientific justification
(maximum 2 pages). Up to 2 additional pages with diagrams may be
included; the
total, including cover sheet, should not exceed 6 pages.
Submit to: Dr. Richard Porcas, EVN Scheduler, MPIfR, Auf dem Huegel 69,
D 53121 BONN, GERMANY or by email to: proposevn@HP.mpifr-bonn.mpg.de.
For further details see http://www.evlbi.org/proposals/prop.html.
Additional information
----------------------
The detailed "Call for Proposals" has further information on Global
VLBI, EVN+MERLIN and guidelines for proposal submission: see http://www.obs.u-bordeaux1.fr/vlbi/EVN/call-long.html.
The EVN User Guide (http://www.evlbi.org/user_guide/user_guide.html)
describes the network and provides general information on its
capabilities.
The EVN Status Table (http://www.mpifr-bonn.mpg.de/EVN/EVNstatus.txt)
gives current antenna capabilities.
The On-line VLBI catalogue (http://db.ira.cnr.it/evn//)
lists sources observed by the EVN and Global VLBI.
The meeting was also the last one chaired by Willem Baan. As Vice-Chairman of Willem during his term, I would like to thank him on behalf of the Member of the EVN Board for the great job he has done. It was a period of huge changes for the EVN, changes planned to mantain the observing facility at the state of the art and to make the VLBI observations more user friendly and realiable.
At the meeting in HartRAO, Raphael Baciller was appointed as Vice-Chairman of the EVN with unanimous vote of the Executive members. Raphael and myself are in charge since July 1st and soon we will start to work for the preparation of the next EVN Board meeting which will be hosted by the Max-Planck fuer Radioastronomie, Bonn, on kind invitation of Anton Zensus. The meeting is planned for November 29th in between the RadioNet meeting (November 28th) and the JIVE Board (November 30th).
As a final note, I would like to wish all the best for the future to all the people involved at various level in the EVN activities and to all users of this wonderful observing facility.
Franco Mantovani (EVN Chairman)
http://www.mpifr-bonn.mpg.de/div/vlbicor/tog_chair/togreps05/togminutes.txt
and
http://www.mpifr-bonn.mpg.de/div/vlbicor/tog_chair/togreps05/index.html
The EVN is working towards full automation within 6 months of "near real-time" fringe checks for recording rates to 1Gbps. The availability of these procedures will allow fringe-finder samples from all observations to be evaluated, giving a nearly continuous monitor on EVN performance.
Following the firmware upgrade to the MkIV decoder, phase cal signals can be used to continuously monitor the LO chain. Scripts are being developed to perform this and other checks, giving a colour-coded performance monitor for station operators.
Network reliability continues to improve, particularly data loss due to human error has decreased. Amplitude calibration has also improved, however the goal of less than 10% scaling at all frequencies has not yet been achieved. More effort will e required, particularly at 22GHz.
Tests of phase-referencing at 22 GHz were successful. The results were summarised in a document by Brunthaler and Paragi available on the EVN webpages. It is expected that phase-referencing at 22 GHz will profit enormously from the ongoing efforts to develop techniques in the framwork of Radionet to measure tropospheric delay and opacity changes.
Due to slewing limitations the Lovell telescope cannot be used for phase-referencing observations at 5 GHz. Garrington and others are developing and testing a scheme using a combination of the Lovell and MK2 telescopes to overcome this limitation. It is expected the a simple observing recipe for the user will be offered in 2006
Automatic flagging works well at nearly all stations except for the Westerbork array, which cannot use standard schemes. At the TOG meeting a flagging scheme for Westerbork was discussed and will probably be implemented soon.
The Mark 5B system is in its final stages of debugging (see report by Alan Whitey). It is expected that the system will become available at the end of 2005.
All 2005 observations are disk-only except for those being sent to the VLBA correlator. It is planned that the EVN will "ramp up" to 1 Gbps recording as the default for continuum observations. The Directors have agreed to purchase the necessary disk space to accommodate this. The Mark 5 system is stable except for some communication problems with the Field System observed in the last session.
The Field System and Sched now fully support disk observations and recording bitrates up to 1024 Mbps. Also features for supporting near-real-time fringe checks and eVLBI are being implemented.
The digital baseband converter project lead by Tuccari(Noto) has been officially approved by the EVN Board. deployment of prototype dBBCs is expected for 2006. Together with the Mark 5B systems this would form a complete VLBI data acquisition system, allow new telescopes to participate in VLBI observations with the EVN.
Walter Alef (TOG
Chairman)
In
March earlier this year, a large funding proposal to support the
e-VLBI activities of the EVN was submitted to the Research
Infrastructures
(Communication Network Development) programme of the
EC. The proposal is called EXPReS (Express Production
Real-Time e-VLBI service) and a few months ago we heard that
it had been well rated. In fact of the 43 proposals submitted to this
call, EXPReS came out TOP of the entire evaluation process,
and as a result will be almost fully funded – to the tune of ~ 4
Million Euro over the next 3 years!
EXPReS will support various aspects of the current e-VLBI programme, including: (i) the upgrade of the EVN correlator at JIVE into a real-time, e-VLBI data processor and an investigation of optimum data transfer protocols and the use of switched light-path technology (led by Dr. Arpad Szomoru, JIVE), (ii) partial support for last-mile connections to radio telescopes in Europe but also China, South Africa, Puerto Rico, Australia and Chile (led by Dr. F. Colomer, OAN), (iii) research into distributed correlation using Grid resources and a study of realising e-VLBI data rates of 10 Gigabits per second (led by Dr. H.J. van Langevelde, JIVE). The overall project coordination will be led by JIVE (Dr. M.A. Garrett)
Mike Garrett (JIVE)
The last e-VLBI
session before this summer was the highly succesfull demo during the EC
PR event as reported elsewhere in this newsletter. Although the
datarate was modest (5 telescopes at 32 Mbps) the system performed
flawlessly.
Until the EXPReS project gets underway, e-VLBI development will focus
mainly on improving the stability and reliability of the system. A
series of tests has been scheduled for the rest of this year, the first
of which was conducted on the 8th of September. Participating stations
were Onsala, Torun, Westerbork, Cambridge and Jodrell Bank (MkII).
Fringes were detected on baselines to four telescopes at 128 Mbps.
Three telescopes transferred data succesfully at a datarate of
256 Mbps, one telescope (Westerbork) even achieved 512 Mbps. Of the UK
telescopes Cambridge was connected to JIVE via a dedicated lightpath
(through UKLight and Netherlight) instead of the regular production
network. Both connections performed well, without any obvious large
differences.
As we are in the process of upgrading the e-VLBI-specific test version
of the correlator control software to a production version, quite a
large portion of the last test was used for debugging. With this out of
the way, we hope in the future to have more time for testing different
configuration schemes, to enable the long uninterrupted runs needed for
science operations.
Arpad Szomoru (JIVE)
TABLE 1: SESSION STATISTICS
---------------------------------------------
SESSION LENGTH NO. SCHEDULED SCHEDULING
(days) FREQ. DAYS EFFICIENCY
VLBI + CAL
---------------------------------------------
may02 15 3 8.4 56 %
nov02 14 3 8.8 + 0.3 65 %
feb03 17 3 2.4 + 0.3 16 %
may03 21 4 14.1 + 0.6 70 %
oct03 18 3 9.7 + 0.9 59 %
feb04 16 4 6.7 + 0.6 46 %
may04 21 3 10.5 + 0.5 52 %
oct04 22 4 15.2 + 0.9 73 %
feb05 21 4 11.1 + 0.7 56 %
jun05 12 2 8.5 + 0.4 74 %
TOTAL 177 33 95.4 + 5.2 57 %
---------------------------------------------
TABLE 2: EVN OBSERVATIONS
--------------------------------
may02-jun05 N-OBS HOURS DAYS
--------------------------------
TOTAL 210 2290.7 95.4
EVN-only 103 1421.2 59.2
GLOBAL 57 681.0 28.4
Short Obs. 3 13.0 0.5
Tests 47 175.5 7.3
Bonn-Corr. 15 257.0 10.7
EVN-Corr. 164 1688.2 70.3
VLBA-Corr. 31 345.5 14.4
EVN+MERLIN 46 598.5 24.9
Eb 186 2110.7 87.9
Wb 171 1846.2 76.9
Jb 185 1986.7 82.8
Cm 93 998.2 41.6
On 176 1960.2 81.7
Mc 182 2022.2 84.3
Nt 154 1692.7 70.5
Tr 138 1527.2 63.6
Ur 88 936.0 39.0
Sh 77 821.0 34.2
Hh 71 610.0 25.4
Ar 30 86.5 3.6
Yb 3 51.0 2.1
Mh 18 216.0 9.0
Wz 3 72.0 3.0
Ro 19 205.0 8.5
--------------------------------
TABLE 3: USER OBSERVATIONS
--------------------------------
may02-jun05 N-OBS HOURS DAYS
--------------------------------
TOTAL 163 2115.2 88.1
EVN+MERLIN 40 572.5 23.9
Continuum 109 1454.0 60.6
Spec. Line 54 661.2 27.6
Bonn-Corr. 14 253.0 10.5
EVN-Corr. 118 1516.7 63.2
VLBA-Corr. 31 345.5 14.4
Wavelength:
1.3 cm 11 176.0 7.3
5 cm 16 181.0 7.5
6 cm 51 652.5 27.2
3.6/13 cm 11 177.5 7.4
18/21 cm 61 804.2 33.5
30 cm 3 35.5 1.5
90 cm 10 88.5 3.7
--------------------------------
TABLE 4: EVN+MERLIN OBSERVATIONS
--------------------------------
N-OBS HOURS DAYS
--------------------------------
TOTAL 40 572.5 23.9
1.3 cm 1 13.0 0.5
5 cm 6 91.0 3.8
6 cm 8 120.0 5.0
18/21 cm 25 348.5 14.5
Continuum 24 362.5 15.1
Spec. Line 16 210.0 8.8
--------------------------------
7. Medicina: a railorad makes
the VLBI pathlength longer
The
Regional Council of Emilia-Romagna with the aim to provide wide band
network links to
all the municipalities in the region, decided to let
the Universities and Scientific Organisations to use such fiber
link. The project plans to provide a dark optical fiber link between
the
POP Garr located in Bologna and the VLBI antenna in Medicina. Ground
work to bury the optical fiber started in early 2003, and in May 2005
the fiber link between the town of Medicina and the Antenna (6 km
apart) has been completed. Unfortunately, problems related to the
planned fiber path which should have crossed a railroad have
temporarily stopped the attempt to bring a direct link from Bologna to
Medicina following the shortest way (30 km). At the moment we are
exploring the possibility to activate a temporary path through
Lugo-Faenza-Imola, implying a total length of about 100 km. This new
path would require devices for signal amplification, but could be
available in a few weeks. As soon as permissions to cross the railroad
path is awarded, the much shorter path, as originally planned,
will be completed and
activated.
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