Call for Proposals for the Interferometer

Observing proposals are invited for the IRAM Plateau de Bure Interferometer (PdBI), for the period May 15, 1994 to November 15, 1994. The deadline for applications is Tuesday, March 1st 1994 . The available frequency range will be 82 GHz to 116 GHz.

Details of PdBI and operations are given in the document ``An Introduction to the IRAM Plateau de Bure Interferometer''. Proposers should read this document carefully before submitting any proposal.

Proposals should be sent to IRAM Scientific Secretariat
Interferometer Observing Proposal
300 Rue de la Piscine
F-38406 Saint Martin d'Hères Cedex
FRANCE

IRAM expects to schedule and complete between 10 to 20 projects in this period, with an elapsed time of at least two months between start and end of any given project. Selection will be based on scientific merit, technical feasibility, and adequacy to the instrument.

2mm For this call for proposals, please note the following:

Change of scheduling periods:

IRAM will now issue 2 calls for proposals per year, instead of 3. The two scheduling periods are 15-May to 15-Nov (``Summer Period''), and 15-Nov to 15-May (``Winter Period'').

Weather:

During the next period ``summer conditions'' will prevail for most of the time. Accordingly, there are severe limitations on the feasibility of high frequency (100 GHz or above), high resolution (BC set) maps. The long baseline parts of such maps may become possible only in September or later. Possible conflicts with sun avoidance should be checked.

Antennas:

Although we will in general carry out the projects with 4 antennas, only 3 antennas will be available during about 6 to 8 weeks in June and July for maintenance reasons.

Time fillers:

Because of the summer conditions mentioned above (weather and antennas), projects which can be carried out with 3 antennas (detections, snapshots, and in general all projects for which the UV coverage is not critical) are strongly encouraged. Projects for which self-calibration is possible will also be favored.

Configurations:

The exact configuration scheme is given in the ``Interferometer'' section of this Newsletter. The ``CD'' (compact) array is obtained with 3 configurations, and the ``BC'' (high resolution) array with 4 configurations, with two configurations in common.

We insist that authors must specify and CAREFULLY justify the requested configuration choice.

Many proposals have been received with insufficient noise estimates. In many cases, a better result can be obtained using lower angular resolution. As a guideline, remember that above 113 GHz, no high resolution maps have yet been produced... Combination of all configurations (BCD, 5 configurations in total), is possible, but must be justified even more carefully.

Coordinates and Velocities:

The interferometer will now operate in the J2000.0 system. For best positioning accuracy, source coordinates MUST be in the J2000.0 system; position errors up to may occur otherwise.

Please do not forget to specify LSR velocities for the sources. For pure continuum projects, the ``special'' velocity NULL (no Doppler tracking) can be used.

New Correlator:

The correlator has 6 independent units, each being tunable anywhere in the 130-610 MHz band, and providing 4 choices of bandwidth/channel configuration: 160 MHz/64, 80 MHz/128, 40 MHz/256 and 20 MHz/256. For the 40, 80 and 160 MHz bandwidths, the two central channels may be perturbed by the Gibbs phenomenon (depending on continuum strength): it is recommended to avoid centering the most important part of the lines at band center.

Receivers:

All receivers can be tuned in lower sideband with USB rejection of 5-8 dB. In this mode system temperatures () below 150 K for A#2 and A#3, and 180 K for A#1 (Trec 45 and 55 K, respectively), are normally reached below 100 GHz. Higher rejections offer no gain in sensitivity. Accordingly, observations are preferentially done in LSB. If you want a double-sideband tuning (e.g. to observe one spectral line in each band), please specify it.

This LSB tuning is not possible above 113 GHz: these frequencies are available only in upper sideband.

Sun Avoidance:

For safety reasons, the sun avoidance circle has been extended to 45 degrees. Please take this into account for your sources AND for the calibrators.

Mosaics:

The PdBI has mosaicing capabilities, but the pointing accuracy may be a limiting factor at the highest frequencies. Please contact S.Guilloteau in case you have questions.

Data reduction:

Proposers should be aware of constraints for data reduction:

• In general, data will be reduced in Grenoble. Proposers will not come for the observations, but will have to come for the reduction.
• We keep the data reduction schedule very flexible, but wish to avoid the presence of more than 2 groups at the same time in Grenoble. Please contact us in advance.
• IRAM may consider splitting the data reduction in two phases: intermediate calibration and final mapping. Such a splitting is often absolutely necessary for the high resolution images. In such a case, the proposers must be ready to come to IRAM for fast data reduction of the ``compact'' configurations (C1 and C2).
• CLIC has been modified to handle the new correlator data. The new version is upward compatible with the previous, but the reverse is not true. Observers wanting to finish data reduction at their home institute should obtain an updated version of CLIC, which is now available. Since CLIC maintenance is a heavy and tricky task, we insist that observers having a copy of CLIC take special care in maintaining it up-to-date.

Data reduction will be carried out on the dedicated HP workstation.

Local contact:

Depending upon the program complexity, IRAM may suggest an in-house collaborator instead of the normal local contact.

Technical screening:

All proposals are analysed by the program committee with respect to their scientific merit and their technical feasibility. Please, help in this task by submitting technically precise proposals by giving exact positions, frequencies and velocities. Please, note that scientific justifications should be kept within 2 pages.

Non-standard observations:

Please contact S.Guilloteau in case of doubt about the feasibility of non-standard programs.

The documentation for the IRAM Plateau de Bure interferometer includes documents of general interest to potential users:

• ``An Introduction to the IRAM Plateau de Bure Interferometer''.
• ``IRAM Plateau de Bure Interferometer: Calibration CookBook''.
• ``IRAM Plateau de Bure Interferometer: Mapping CookBook''.
• ``IRAM Plateau de Bure Interferometer: Frequency Setup''
• ``CLIC: Continuum and Line Interferometer Calibration''

• ``IRAM Plateau de Bure Interferometer: OBS Users Guide''
• ``IRAM Plateau de Bure Interferometer: Amplitude Calibration''
• ``IRAM Plateau de Bure Interferometer: Flux Measurements''
• ``IRAM Plateau de Bure Interferometer: Pointing Parameters''
• ``IRAM Plateau de Bure Interferometer: Trouble Shooting Guide''