next up previous
Next: IRAM Progress Report FP6 Up: IRAM Newsletter 61 (December 2004) Previous: Bolometer mapping - rotated


VLBI observations and Call for Proposals

October 2004 VLBI session

Both IRAM instruments were participating successfully in the Global October VLBI session, together with the stations of Effelsberg, Onsala, Metsahovi and the VLBA.

The Plateau de Bure was operating with the EFOS-1 maser (Fig. 3) which will return to the geodetic station of Wettzell in mid-2005. The previous maser has been repaired by J.-M. Torre at the OCA (Observatoire de la Cote d'Azur), and is ready to go up to the observatory.

Every VLBI session demands a joint effort of telescope operators, technicians, astronomers and schedulers, which extends well beyond the duration of the actual observations. The October 2004 session was unusual due to its length of nearly 6 days and several observing frequency changes, and the absence of breaks in the schedule. Technical tasks had to be anticipated and moved carefully to make room for several days of uninterrupted observations. Bure and Pico Veleta observatories were assisted by personnel from MPIfR Bonn. Many thanks to all those who have made these observations possible.

Michael Bremer

Figure 3: The EFOS-1 maser in the PdBI correlator room. The maser itself is mounted on two stages of shock absorbers, which protect the frequency standard during its transport by road and helicopter. Its power supply can be seen in the background. To the right, the rack with the frequency synthesizers is installed, together with the computer which monitors the operating parameters of the maser.
\end{center} \end{figure}

Call for Global VLBI Proposals at 3mm wavelength

We announce the opportunity for coordinated, high angular resolution and high sensitivity GLOBAL VLBI observations in the 3mm band (85 - 95 GHz), complementing existing stand-alone VLBA observations at these frequencies. The Global 3mm VLBI Array consists of 8 VLBA antennas equipped with 3mm receivers, plus the IRAM 30-m telescope on Pico Veleta (Spain), the IRAM phased 6-element interferometer on Plateau de Bure (France), the 20-m radio telescope in Onsala (Sweden) the 14-m telescope in Metsähovi (Finland) and the MPIfR 100-m radio telescope in Effelsberg (Germany). Other telescopes may join later.

The Global 3mm VLBI Array is the successor to the former Coordinated Millimeter VLBI Array (CMVA) and offers 3 to 4 times more sensitivity than the stand-alone VLBA. Observations with the Global 3mm VLBI array will be scheduled in time blocks in special observing sessions, performed twice per year. The next two sessions are tentatively planned for April 15-20, 2005 and October 13-19, 2005. The actual duration of each session will depend on proposal pressure.

The Global 3mm VLBI Array basically supports the same observing modes as the VLBA. For standard continuum observations the VLBI recording will be done at 256 Mbit/s (corresponding to a bandwith of 128 MHz). Recording at 512 Mb/s is now offered as a standard mode for continuum observations in order to maximize the instantaneous sensitivity, but with the limitation of an equivalent data volume of not more than 2 tapes in 24hrs, to allow for those VLBA stations which still record exclusively on tapes.

Correlation will be performed in absentia at the MPIfR MK4 correlator in Bonn unless some technical reason for using another correlator is given in the proposal. The P.I. will receive the correlated data in uv-fits format.

Proposals for the October 2005 session should be prepared in a similar fashion as ``normal cm-VLBI proposals'', using the standard VLBI cover sheet and instructions available on the web under URL and should be submitted electronically as e-mail before

Tuesday, February 1st 2005, before 22:00 UT
(17:00 US Eastern Standard Time)

to the following two addresses (in copy):

Proposals will be reviewed by NRAO and the participating European Observatories.

The European Schedule Coordinator, Dr. R. Porcas (MPIfR), will forward proposal copies to the participating European Institutes and ensure the scientific evaluation of the proposals by the respective local committees. Finally, the referee ratings of these observatories and the NRAO will be combined.

Global VLBI observations at 3mm are subject to some technical restrictions, which are summarized on the following web-page


The IRAM and MPIfR VLBI teams

Some useful web pages

VLBI observations allow unique insights in the astrophysics of compact and bright sources. Please prepare your proposals carefully, as they are equivalent to asking simultaneously for observing time on a large number of telescopes. Avoid last minute submissions: the e-mail submission may bounce large e-mails (critical limit about 5 Megabytes), returning them with details on how to submit via anonymous FTP. See for more information.

Michael BREMER

next up previous
Next: IRAM Progress Report FP6 Up: IRAM Newsletter 61 (December 2004) Previous: Bolometer mapping - rotated