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Winter Experience

Last winter, the interferometer has been in long baselines configurations (A1 and A2) for longer than expected, because large amounts of snow prevented moving the antennas. As a result, the B1 and B2 configurations could only be scheduled relatively late during the spring, when weather conditions were not very favorable for 1.3mm projects.

Preliminary analysis of the very long baseline data (A-configurations) carried out in Jan-Feb indicates that sub-arcsec angular resolution was indeed achieved, with good phase stability even at 230 GHz on several projects (but unfortunately not all). Since such high angular resolution is very sensitive to weather conditions, we expect better results next winter due to the advent of antenna 5, which will allow long baselines observations to be carried out in a single configuration.

1.5'' resolution at 230 GHz (CD array) was routinely achieved during this winter, even on relatively ``low'' declination sources.

The ``active'' phase correction system has been useless in winter (the weather was too good !), but became very useful in the spring. Software has been written to optimize its use, and is now available in the standard CLIC package.