Call for Proposals on the Plateau de Bure Interferometer

Conditions for the next summer period

As every year, we plan to carry out extensive technical work during the summer period. Besides the usual maintenance of the antennas we plan to complete the northern track extension, prepare N46 - the new station at the end of the northern track - for the next winter period, and procede with the drilling of the elevator shaft for the new access to the Plateau de Bure Observatory.

Despite these technical activities, we plan to carry out regular scientific observations during the whole period with the five element array. Taking these considerations into account, we are confident to be able to schedule about 20 to 30 projects.

We plan to start the maintenance at the latest by the end of May and to schedule two configurations (C and D) between June and October. For observers interested in high-angular resolution studies, we tentatively plan a switch back to the six element array and move to an extended configuration (B) for the end of October, i.e. before the end of the scheduling period.

We strongly encourage observers to submit proposals that can be executed during summer operating conditions. To keep the procedure as simple as possible, we ask to focus on:

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observations requesting the use of the 3mm receivers

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circumpolar sources or sources transiting at night between June and September,

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observations that qualify for the CD configuration with 5 antennas.

Details on receivers, signal to noise, atmospheric phase compensation, observing modes, data reduction and local contacts have not changed, and can be found in the January 1999 issue of the IRAM Newsletter. For this call for proposals, please note the following specificities:

Configurations

Standard configurations for the summer period are:

5 antenna configurations
Name	Stations
D	W05 W00 E03 N05 N09
C	W12 W09 E10 N05 N15
B	W12 E18 E23 N13 N20

Part of the projects will be scheduled at the end of the summer period when the six-element array is expected to be back to operation. Projects that should be observed with four antennas only, will be adjusted in uv-coverage and observing time.

The following configuration sets are available:

Set	Main purpose
D	``Low'' resolution at 1.3 mm
CD	3.5'' resolution at 3mm
BC	2'' resolution at 3 mm

Finally, enter ANY in the proposal form if your project doesn't need any particular configuration. Note, that the B configuration will become available only at the very end of the summer period depending on weather conditions and pressure on the C and D configurations.

Correlator

The correlator has 8 independent units, each being tunable anywhere in the 110-680 MHz band, and providing 7 different modes of configuration (characterized in the following by couples of total bandwidth/number of channels). In the first 3 modes (LSB+USB): 320MHz/128, 160MHz/256, 80MHz/512 the two central channels may be perturbed by the Gibbs phenomenon (depending on continuum strength) like in the old correlator. When using these modes, it is recommended to avoid centering the most important part of the lines in the middle of the band of the correlator unit. In the remaining modes (LSB or USB): 160MHz/128, 80MHz/256, 40MHz/512 and 20MHz/512 the two central channels are not affected by the Gibbs phenomenon and, therefore, these modes should be preferred for spectroscopic studies. The 8 units can be independently placed either on the IF1 (3mm receiver) or on the IF2 (1.3mm receiver). For more details, please refer to the Web page at http://www.iram.fr/IRAMFR/TA/backend/cor6A/.

Roberto NERI