European VLBI Network
Edited by Andrei Lobanov, MPIfR Bonn (email@example.com)
Message from the Chairman
of the EVN Board of Directors
We are saddened to hear from our colleagues in South Africa of the passing of Mike Gaylard. As Director of Hartebeesthoek Radio Observatory he worked with us in the EVN CBD and JIVE Board since our 2011 meetings in Torun until this year. At that time he requested full membership for HartRAO in the EVN. The photo shows him on the occasion of signing the participation of HartRAO in JIVE, in Bonn in 2012. In his place, Prof. Ludwig Combrinck (firstname.lastname@example.org) has been appointed as Acting Managing Director of HartRAO until further notice.
In November we go again to Italy, to Bologna for the EVN Consortium Board of Directors Meeting on the 5th, followed by the JIVE Board meeting on the 6th. The EVN Program Committee also plans to meet in Bologna on this date. In the same week there is a special meeting for DiFX correlator operators/users in Bologna. And then some must rush up to Groningen (The Netherlands) in the following week for the 3rd International VLBI Technology Workshop.
In case anyone thinks that the EVN and VLBI consists of only meeting and eating, it's worth pointing out that in the same period there are two e-VLBI sessions (8/9 October and 18/19 November) and, of course, EVN Session III (16 October to 6 November) which this time has projects scheduled at 7mm and 3.6, 5, 6 and 18cm, including one observation together with RadioAstron.
This call is also available on the web at
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 observations may be conducted with disk recording (standard EVN) or in real-time (e-VLBI).
The EVN facility 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.
Standard EVN Observing Sessions (disk recording)
2015 Session 1 Feb 26 - Mar 19 18/21cm, 6cm ...
2015 Session 2 May 28 – Jun 18 18/21cm, 6cm ...
2015 Session 3 Oct 15 - Nov 05 18/21cm, 6cm ...
Proposals received by 1st
October 2014 will be considered for scheduling in Session 1, 2015 or later. Finalisation of the planned observing wavelengths will
depend on proposal pressure.
e-VLBI Observing Sessions (real-time correlation)
2014 Nov 18 – Nov 19 (start at 13 UTC) 18/21cm, 6cm, 5cm or 1.3cm
2014 Dec 02 – Dec 03 (start at 13 UTC) 18/21cm, 6cm, 5cm or 1.3cm
2015 Jan 13 – Jan 14 (start at 13 UTC) 18/21cm, 6cm, 5cm or 1.3cm
2015 Feb 10 – Feb 11 (start at 13 UTC) 18/21cm, 6cm, 5cm or 1.3cm
2015 Mar 24 – Mar 25 (start at 13 UTC) 18/21cm, 6cm, 5cm or 1.3cm
Please consult the e-VLBI web page at http://www.evlbi.org/evlbi/e-vlbi_status.html to check for possible updates, and for the available array.
Successful proposals with an e-VLBI component submitted by the October 1st deadline will be considered for scheduling in the above e-VLBI sessions starting from Nov 18th 2014.
Note that only one wavelength will be run in each e-VLBI session, depending on proposal priorities.
See http://www.e-merlin.ac.uk/vlbi/evn_docs/guidelines.html for details concerning the e-VLBI
observation classes and observing modes
for the Next Regular EVN and e-VLBI Sessions
* Both Jb1 and Jb2 will be available for EVN recording, as will simultaneous EVN+e-MERLIN operations with home-station EVN recording. For such simultaneous EVN+e-MERLIN operations, VLBI data from Cm will be made available at up to 512 Mbps (e.g. 64 MHz in both hands of circular polarization) on a best efforts basis.
For updated information please consult the web at: http://www.e-merlin.ac.uk/vlbi/
* Please consult http://www.evlbi.org/evlbi/e-vlbi_status.html and the EVN User Guide http://www.evlbi.org/user_guide/user_guide.html for updates on the current EVN and e-VLBI
array, availability of different stations per observing band and for the
dates of the e-VLBI observing sessions.
* Global proposals can be proposed up to 1 Gb/s including VLBA,GBT,JVLA
* Some modes may require different bandwidth channels from EVN & NRAO telescopes; correlation at JIVE can handle this
* JIVE support staff and Amy Mioduszewski at Socorro will assist during the scheduling process of such observations.
* Global observations will
be correlated at the SFXC correlator at JIVE
(default) or at the DiFX correlator
in Bonn (if appropriate justification is given in the proposal).
* Proposals requesting the
EVN as ground array support for RadioAstron
proposals for the latter part of the AO2 period (1 July 2014 - 30 June 2015)
may still be submitted at this deadline
* 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.
of EVN Antennas
* Medicina and Urumqi should return to the EVN from Session 1, 2015 onwards. The Sardinia 64m telescope (SRT) remains in a commissioning phase but is available on a "best efforts" basis from Session 1, 2015. Robledo 70m telescope is occasionally available for EVN observations. From Session 1, 2015, the availability of WSRT as a phased array is not certain and WSRT may be participating with a single telescope.
* The new 65m Tianma (Shanghai) telescope will become available for EVN
operations from Session 1 2015. See the EVN Status Table for details.
of Korean VLBI Network Antennas
* The Korean VLBI Network
(KVN) has now become an Associate Member of the EVN (as from January 2014).
KVN telescopes may be requested for EVN observations at 1.3cm and 7mm
wavelengths. For more details regarding the KVN, see: http://kvn-web.kasi.re.kr/en/en_normal_info.php
of Australian VLBI Network Antennas
* It is planned that starting in Session 1 2015, some Australian Long Baseline Array (LBA) time will be made available for simultaneous scheduling with the EVN, thus enabling the possibility of joint LBA/EVN observations in that and future disc sessions. The easternmost stations of the EVN are in a similar longitude range to the LBA telescopes, and for sources in equatorial regions, baselines to western European stations are also achievable. Joint LBA time is likely to be heavily oversubscribed, and authors are requested to note whether they are prepared to accept scheduling without LBA antennas being present. Proposals for joint LBA/EVN observations in session 2/2015 must be submitted separately to both the LBA and EVN:
LBA in their 15 Dec 2014 deadline.
EVN in either their 1 Oct 2014 or 1 Feb 2015 deadlines.
For more details regarding
proposing time on the LBA, see: http://www.atnf.csiro.au/observers/apply/avail.html
EVN+LBA observations should
be possible at all principal EVN wavebands from 21 cm to 1.3 cm.
of Session Observing
* Out-of-Session observing
time (up to a maximum of 144 hours/year), is now available to all proposals.
Proposals requesting Out-of-Session observing time must provide full
scientific (and technical if appropriate) justification as to why
observations must be made outside regular sessions. Out-of-Session observing
blocks should be no less than 12 hours in duration (although individual
observations can be shorter), and occur no more than 10 times per year (up to
a maximum of 144 hours). Proposals should specify which dates/GST ranges are
being requested and indicate the minimum requirement in terms of numbers of
telescopes (and any particular telescopes). Proposals will only be considered
for dates occurring after the regular EVN session that follows the proposal
deadline. Observations requiring much shorter lead times should be submitted
as "Target-of-Opportunity" proposals.
All EVN and Global proposals (except ToO proposals) must be submitted using the NorthStar on-line proposal submission tool. Global proposals will be forwarded to NRAO automatically and should not be submitted to NRAO separately.
When specifying your
"Recording format" for Global modes in the EVN proposal tool,
select 32. 64. 128, 256, 512, or 1024 Mbps from the "Specify aggregate
bitrate (use network defaults)" menu.
The SCIENTIFIC JUSTIFICATION MUST BE LIMITED TO 2 PAGES in length. Up to 2 additional pages with diagrams may be included.
When specifying requested antennas from the LBA, please specify 'LBA' under the "other" row in the telescope-selection box – this selects all that are available for joint observations.‘
The deadline for submission
is 23:59:59 UTC on 1st October 2014.
Further information on Global VLBI, EVN+MERLIN and e-VLBI observations, and guidelines for proposal submission are available at: http://www.e-merlin.ac.uk/vlbi/evn_docs/guidelines.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 current antenna
capabilities can be found in the status tables. For the standard EVN see
For the e-EVN array see http://www.evlbi.org/evlbi/e-vlbi_status.html.
The On-line VLBI catalogue (http://db.ira.inaf.it/evn/) lists sources observed by the EVN and Global VLBI.
EVN and eMERLIN constrain the progenitor
system and environs of SN 2014J
Type Ia supernovae (SNe) are the end-products of white dwarfs with a mass approaching the Chandrasekhar limit, which results in a thermonuclear explosion of the star. In addition to their use as cosmological distance indicators Type Ia SNe are a major contributor to the chemical evolution of galaxies. It is therefore unfortunate that we do not yet know what makes a SN Ia. This lack of knowledge makes it difficult to gain a physical understanding of the explosions, so that we can model possible evolution, which compromises their use as distance indicators. It also means we do not fully understand the timescale over which SNe Ia turn on, adding a large uncertainty to our understanding of the chemical evolution of galaxies.
Figure 1. eEVN and eMERLIN images of SN 2014J in M82, combined with an optical image of the host galaxy.
Observations can potentially discriminate between the progenitor models of SNe Ia. For example, in all scenarios with mass transfer from a companion, a significant amount of circumstellar gas is expected, and therefore a shock is bound to form when the supernova ejecta are expelled. The situation would then be very similar to circumstellar interaction in core-collapse SNe, where the interaction of the blast wave from the supernova with its circumstellar medium results in strong radio and X-ray emission. On the other hand, the DD scenario will not give rise to any circumstellar medium close to the progenitor system, and hence essentially no radio emission is expected.
SN 2014J in M82 (D=3.5 Mpc) has brought us a unique opportunity to severely constrain the plethora of theoretical models proposed as potential progenitor systems for Type Ia SNe.
Figure 2. Constraints on the parameter space (wind speed, , vs. mass-loss rate, ) for single degenerate scenarios for SN 2014J. The progenitor scenarios are plotted as schematic zones, and we indicate our 3σ limits on assuming two different fractions of the energy density in magnetic fields to the total post-shock supernova energy density, namely (solid) and the conservative case of (dashed). Mass loss scenarios falling into the gray shaded areas should have been detected by our deep radio observations, and therefore are ruled out for SN2014J. For a comparison, we include our reassessed limit for SN 2011fe (dash-dotted line) for the same choice of parameters as the solid line for SN 2014J, which essentially leaves only room for quiescent nova emission as a viable alternative among the SD scenarios for SN 2011fe.
We observed SN 2014J with the eMERLIN array on 28-30 Jan 2014 at 1.6 and 6.2 GHz, and with the EVN on 4 Feb 2014 and 19 Feb 2014, at a frequency of 1.7 GHz. Our observations towards the position of SN 2014J were the deepest ever realised with those arrays, yet resulted in non-detections of the SN (see Fig. 1).
Our radio data and modeling allow us to place a tight constraint on the mass loss rate from the progenitor system of SN~2014J. Namely, if the exploding WD was surrounded by a wind with a density profile r µ r-2, as expected for a SD scenario, then our upper limit to the mass-loss rate is , for a wind speed .
If, on the contrary, the circumstellar gas has a constant density, as expected to be the case for the DD scenario (but also in a small region of the parameter space of SD scenarios), then our modeling yields an upper limit on the gas density, such that .
Our stringent upper limits to the circumstellar density around SN~2014J allow us to exclude completely symbiotic systems and the majority of the parameter space associated with stable nuclear burning WDs, as viable progenitor systems for SN 2014J.
For the case of recurrent novae with main sequence or subgiant donors, we cannot rule out them completely, yet most of their parameter space is also excluded by our observations for the standard assumption of , where is the ratio of magnetic energy density to post-shock thermal energy density.
Reference: Pérez-Torres, Lundqvist, Beswick et al. (2014), ApJ, vol. 792, p. 38
Miguel Angel Pérez-Torres (Instituto de Astrofísica de Andalucía, Granada; Centro de Estudios de la Física del Cosmos de Aragón, Teruel, Spain)
Over the past few years, the SFXC software correlator at JIVE has taken over all EVN correlation. In fact, earlier this year the MarkIV hardware correlator was dismantled and removed. A number of correlator boards were shipped to Hawaii, as spare parts for the SMA.
Although not yet generally in operational use, most EVN stations now have digital baseband converters, while the VLBA has completed its upgrade to RDBEs. This is opening the way to increase the bandwidth of EVN and combined EVN-VLBA observations beyond the current 1 Gbps limit. 4 Gbps operations, both recorded and real-time, were successfully demonstrated last year with Effelsberg, Onsala, Metsahovi, Yebes and Hartebeesthoek, showing that technically the EVN is quite ready.
Figure 3. JUC Uniboards.
Figure 4. JUC phases versus time.
While extremely versatile and flexible,
the SFXC is limited in its capability to handle a large number of stations at
high bandwidths in real time. Implementing a 16-station 4 Gbps
real-time correlator would involve a considerable
investment in hardware. And while this situation is bound to improve as
The UniBoard project, a JRA in Radionet FP7, was instigated by JIVE with just this idea in mind. Its aim was to build an FPGA-based high-performance generic computing platform, along with several firmware personalities. The development of a UniBoard-based VLBI correlator by JIVE was further strengthened by funding from NWO and partly through the follow-up UniBoard2 project in RadioNet3.
At this time, the JUC has evolved into an operational correlator, which is now being debugged/commissioned. Recent improvements were the increase of the precision of the delay coefficients and the fixing of several elusive bugs, which have greatly improved the stability of the system. While many interesting problems remain, it has reached the point where an operator can mount disk packs in Mark5 units, select one or more scans of a project and run a correlation job, which then can be further processed in much the same way the SFXC output is handled. Currently the JUC consists of two UniBoard units (Figure 3). In this configuration the JUC can process up to 32 stations, two polarizations and 128 MHz bandwidth (1 Gbps). Once the 32 MHz-subband mode is verified, it will also be able to correlate 16 stations at 256 MHz (2 Gbps) or 8 stations at 512 MHz (4 Gbps).
Note that the two UniBoards together consume a total of about 0.5 kW. Were we to scale both the JUC and the SFXC hardware to 16 stations at 4 Gbps, the JUC would consume 1 kW, in contrast to 30 kW for SFXC.
The current parameters of the JUC correlator are listed in Table 1. Figure 4 shows phases versus time on several baselines of experiment EA053D, demonstrating how well the interferometric phase is tracked.
Arpad Szomoru (JIVE) for the JUC Team
Table 1. JUC specifications
Supported in June 2014
Bandwidth (real time)
Sub-bands (real time)
Input resolution (max)
Integration time (all products)
Data input format
64 MHz (1 UNB)
16 MHz, 32 MHz under test
0.022 s – 1 s
2112 including cross, auto, and cross-polarization
64n MHz (m UNBs)
1, 2, 4, 8, 16, 32, 64 MHz
1, 2, 4, 8 bits
0.022 s – 2 s
<1 kHz spectral mode
VDIF, mixed frame sizes
2014 Session 2: 29 May – 19 June
Wavelengths: 18, 0.7, 6, 5, 90, 1.3cm
Number of different user experiments observed: 29
Session Duration: 21.6 days Efficiency: 52.6%
Breakdown of observations by type and correlator. TBYTES indicates the estimated disk usage (in TB) at EVN telescopes.
may14 N-OBS HOURS DAYS T-BYTES
TOTAL 39 272.5 11.4 989.1
EVN-only 18 176.0 7.3 641.4
Global 11 74.5 3.1 292.5
Short Obs. 0 0.0 0.0 0.0
Tests 10 22.0 0.9 55.2
EVN Correlator 38 259.0 10.8 962.9
Bonn Correlator 1 13.5 0.6 26.2
VLBA Correlator 0 0.0 0.0 0.0
eEVN Correlator 0 0.0 0.0 0.0
Other Correlator 0 0.0 0.0 0.0
CAL-only 5 20.0 0.8 0.0
2014 e-VLBI Observations
e-VLBI PROPOSAL TYPE
RUN DATE WTH HRS Normal Short Disk ToO Trigger
14e06 24JUN14 6cm 24 1 1 - 1 0 sched 0 trig
Reports from EVN Institutes
The conference costs were supported by Torun Centre for Astronomy and RadioNet3 (FP7, contract no. 283393)
Anna Bartkiewicz (Torun Centre for
Figure 6. Photographs from the YERAC-2014 in Torun. The conference photon (top left), science session at the conference (top right), the visit to the TCfA (bottom left) excursion in Torun (bottom right).
On October 7-10, the Istituto di Radioastronomia (IRA) and the Osservatorio Astronomico di Cagliari (OAC) of the Istituto Nazionale di Astrofisica (INAF), on behalf of the European VLBI Consortium, will host the 12th European VLBI Network Symposium and EVN Users Meeting from October 7th to 10th, 2014. Principal sponsors of the event are RadioNet3 and INAF. The Symposium will be held in Cagliari, on the South coast of the island of Sardinia.
At this conference the latest scientific results and technical developments from VLBI, and, in particular, e-VLBI and space-VLBI (RadioAstron) results will be reported. The scientific sessions will cover a variety of topics, including low-luminosity AGN, powerful jets, gamma-ray emission, supernovae, star formation, and current and future technical developments and collaborations. The timing of this meeting coincides with the first successful observational tests of the Sardinia Radio Telescopes within the EVN, and with a number of results from new and upgraded radio facilities around the globe, such as e-MERLIN, ALMA, and the SKA pathfinders. This meeting will also incorporate the EVN Users meeting.Further details about the Symposium are available on the conference website: http://evn2014.oa-cagliari.inaf.it/EVN2014/
East Asia to Italy: Nearly Global VLBI-2014 (Bologna, 13-14 October 2014)
The meeting is supported by
the Italian Ministry for Foreign Affairs, the Department of Physics and
Astronomy of the University of Bologna, and RadioNet3. Further information
about the meeting can be found at its website:
Continued discussion of VLBI technology development will find its next venue on November 10-13 in Groningen, where the third international VLBI technology workshop and a special session on RadioNet3 ERATec engineering will be held. This workshop has grown out of the highly successful 10-years series of e-VLBI meetings which laid the groundwork of cooperation and development in the field of real time VLBI. The present series of workshops expands the scope of discussion to all areas of hardware and software development in VLBI, focusing in particular on the development of global e-VLBI framework for scientific observations.
The third workshop in this
series will review progress in receivers, digital backends,
recording equipment, and e-transport. Specific attention will be given to
discussion of frequency and clock transfers over public networks and current
and future data transport challenges.
At the last day of the workshop, a half-day NREN - radio astronomy
session will be held, organised and sponsored by
GÉANT, the pan-European research and education network.