Since the helicopter accident on December 15th, 1999, no astronomical observations have been carried out with the Plateau de Bure Interferometer. Only observations aiming at testing thoroughly the instrumentation and the recently installed new cross-correlator have been made during these months. The antenna maintenance is now over and regular astronomical observations have restarted, as of December 1, 2000. Users of the Plateau de Bure Interferometer will independently be informed about the restart of the astronomical activities in the days to come.
As announced in the previous issue of the IRAM Newsletter, the CD (C2+D) set of configurations has been planned for the winter period: for practical reasons the interferometer has been moved recently to the C2 configuration and will be moved (depending on weather conditions) to the compact D configuration shortly after the middle of January, 2001. This means that projects aiming at deep integrations and mapping in the D-configuration can certainly not be completed before.
Though regular astronomical observations will be carried out all over the winter period, the safety of the personnel and of the instrumentation will take precedence over observations. For the time being and for the whole winter period, teams consisting of a mechanic, an electrician, a cook, two operators and an astronomer will operate on a weekly basis at the Plateau de Bure observatory to guarantee a regular astronomical activity. We are confident of scheduling all the A-rated projects, but even under best circumstances the number of B-rated projects that can be carried out will be small. We will do our best to keep investigators informed about the status of their projects all along the winter period.
The interferometer was thoroughly maintained during the summer period. Time has essentially been invested to repair and replace equipment, to measure the surface of the antennas and to improve the alignment of the subreflectors. Noteworthy are the replacement of the aluminium subreflector of antenna 3 and, in connection with our plans to extend the capabilities of the Plateau de Bure interferometer, the replacement of the five antenna correlator. The new correlator was installed at the beginning of September and tested extensively during the months of October and November. The new facility was designed to serve on the long-term the six antenna array and the forthcoming generation of broadband receivers, and allows phased array operation for a future VLBI station. As it is largely improving on the old correlator, many of the winter programs will benefit of its extended performance. Noteworthy are the correlator capability to cover simultaneously and completely both receiver passbands (the correlator frequency coverage is 2.4GHz in total), and the fact that any of the eight correlator units is now able to provide the 40KHz spectral high resolution mode over a 20MHz bandwidth.