In October 2002 and April 2003, two global VLBI experiments at 3mm wavelength have taken place involving both IRAM instruments, with the 6-antenna Plateau de Bure in phased-array mode for the first time. The IRAM 30-m telescope has already prooved its value in global VLBI observations for many years, but these two experiments now have shown that also the Plateau de Bure can work reliably as a phased array VLBI station. Two times per year both instruments will be available for global VLBI experiments (see Call for Proposals below).
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 16-21, 2004 and October 8-13, 2004. 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). 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 2004 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 http://www.nrao.edu/administration/directors_office/vlba-gvlbi.shtml and should be submitted electronically as e-mail before
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 (http://www.mpifr-bonn.mpg.de/div/vlbi/globalmm/index.html).
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 http://www.nrao.edu/administration/directors_office/vlba-gvlbi.shtml for more information.