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Call for proposals on the Plateau de Bure Interferometer

Observing proposals are invited for the IRAM Plateau de Bure Interferometer (PdBI) for the period May 15, 1999 to November 15, 1999. The deadline for applications is March 8th, 1999 24:00h (MET)). Applications may now be submitted via the World-Wide-Web using the new electronic proposal submission facility.

IRAM expects to schedule and complete between 30 to 50 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.

Details of the PdBI and the observing procedures are given in the document ``An Introduction to the Plateau de Bure Interferometer''. A copy can be obtained from the address below via Internet (use IRAM's home page at Proposers should read this document carefully before submitting any proposal.

Applications sent by fax or postal mail should be addressed to:

IRAM Scientific Secretariat
Interferometer Observing Proposal
300 Rue de la Piscine
F-38406 Saint Martin d'Hères Cedex

Proposal templates and the Latex style file (proposal.sty) may be obtained by anonymous ftp from (directory dist/proposal) or via the Web at In case of problems, contact the secretary, Cathy Berjaud.

We encourage the use of the electronic submission facility. Proposals sent by e-mail, however, will not be accepted. Do not use characters smaller than 11pt, which could make your proposal illegible when copied or faxed. For the same reasons, also avoid sending by fax figures with grey scale maps. In case your proposal reaches us in time, but is incomplete or unreadable when copied, we will try out best to contact you. The Principal Investigator will receive by return mail an acknowledgement of receipt and the proposal number.

The scientific aims of the proposed programme should be explained on 2 pages of text maximum, plus up to two pages of figures, tables, and references. Proposals should be self-explanatory, clearly state these aims, and explain the need of the Plateau de Bure interferometer.

In all cases, indicate on the first page whether your proposal is (or is not) the resubmission of a previously rejected proposal or the continuation of a previously accepted proposal. In case of a resubmission, state very briefly in the introduction why the proposal is being resubmitted (e.g. improved scientific justification).

For this call for proposals, please note the following specificities.

Backup Projects for the May-Nov. 1999 period

Because of heavy antenna maintenance, not all the backup projects for the summer period will be scheduled. We urge proposers to re-submit them unless they have explicitly been notified of their effective scheduling.

Proposal category

Proposals should be submitted for one of the five categories:

Proposals that ask for 1.3mm data only. 3mm receivers will be used for pointing and calibration purposes, but cannot provide any imaging.
Proposals that ask for 3mm data only. 1.3 mm receivers can still be used to provide either phase stability information or purely qualitative information such as the mere existence of fringes.
dual freq.:
Proposals that ask for dual-frequency observations (i.e. simultaneous observations at 3mm and 1.3mm).
time filler:
Proposals that have to be considered as background projects to fill in periods where the atmospheric conditions do not allow mapping, or eventually, to fill in gaps in the scheduling, or even periods when only a subset of the standard 4 and 5-antenna configurations will be available. These proposals will be carried out on a ``best effort'' basis only.
Exploratory proposals: proposals whose scientific interest justifies the attempt to use the PdB array beyond its guaranteed capabilities. This category includes for example non-standard frequencies for which tuning cannot be guaranteed, non-standard configurations and more generally all non-standard observations. These proposals, if accepted, will be carried out on a ``best effort'' basis.

The proposal category will have to be specified on the proposal cover sheet and should be carefully chosen by the proposers.


Standard configurations for the summer period are:

5 antenna configurations
Name Stations
D W05 W00 E03 N05 N09
C1 W05 W01 E10 N07 N13
C2 W12 W09 E10 N05 N15
B1 W12 E18 E23 N13 N20
B2 W23 W12 E12 N17 N29

Part of the projects will have to be scheduled during the maintenance period (June-September) where only 4-antennas will be available. These projects will be properly adjusted in observing time and uv-coverage.

The following configuration sets are available:

Set Configs Main purpose
D D ``Low'' resolution at 1.3 mm
CD D, C2 or C1 3.5'' resolution at 3mm, 1.8'' resolution at 1.3 mm
CC C1, C2 Slightly higher resolution than CD.
BC B1, C2 2'' resolution at 3 mm
BB B1, B2, C2 Better sensitivity than BC

There is a possibility of choice between CD and CC arrays when the C2 configuration has been performed for sources in which the resolution choice is unclear. At a higher resolution level, a similar choice between CC and BC or BB is possible. Note that configuration A will not be scheduled for the summer session.

Finally, enter ANY in the proposal form if your project doesn't need any particular configuration.


All antennas are equipped with fully operational dual frequency receivers. The available frequency range will be 82 GHz to 116 GHz for the 3mm band, and 210 to 245 GHz for the 1.3 mm band. The 3mm and 1.3mm receivers are aligned to within about 2''.

Below 110 GHz, receivers offer best performances in LSB tuning with high rejection (20 dB): expected system temperatures are 100 to 200 K ( tex2html_wrap_inline2191 scale) for the summer time. Above 110 GHz, best performances are obtained with USB tuning, low rejection (4 to 6 dB): expected system temperatures are 300 K at 115 GHz. DSB tuning is possible over the whole frequency range, but the system temperature may degrade significantly.

The 1.3 mm receivers give DSB tuning with typical T tex2html_wrap_inline2193 below 50 K. Expected SSB system temperatures are 400 to 500 K. The guaranteed tuning range is 210-245 GHz, but it may be possible to reach lower frequencies for specific cases. Higher frequencies are not feasible because of limitations in the triplers.

1.3mm band observations

Experience based on the past years shows that 1.3 mm observations are seldom feasible in summer time, and that such observations are possible only for objects transiting during the night of the August to October period. Accordingly, 1.3mm or dual-frequency projects for other objects will be considered as ``Category 4'' proposals, i.e. will be carried out on a best effort basis only, weather permitting.

Note that the field of view at 1.3 mm is very restricted (about 20'').

Atmospheric phase compensation

Software is available to provide real-time atmospheric phase compensation on spectral and continuum data, as well as a-posteriori processing for continuum data. Experience shows that a final phase noise below 30 degrees at 230 GHz is obtained under favorable circumstances.

Signal-to-Noise ratio

The rms noise can be computed from



Coordinates and Velocities

The interferometer operates in the J2000.0 system. For best positioning accuracy, source coordinates must be in the J2000.0 system; position errors up to 0.3'' 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.

Coordinates and velocities in the proposal MUST BE CORRECT: A coordinate error is a potential cause for proposal rejection.


The correlator has 6 independent units, each being tunable anywhere in the 110-610 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 in the middle of the band of the correlator unit.

The 6 units can be independently placed either on IF1 (3 mm receiver) or on IF2 (1.3 mm receiver).

40 KHz resolution

One (and only one) of the 6 units has been retrofitted to offer a higher frequency resolution (40 kHz instead of 80 kHz). This is obtained by operating at half clock speed and inserting an anti-aliasing filter of effective bandwidth 8 MHz. Because the filter reduces the input power to the sampler, this unit should be placed near the maximum amplitude of the IF bandpass: band edges must be avoided.

Sun Avoidance

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


The PdBI has mosaicing capabilities, but the pointing accuracy may be a limiting factor at the highest frequencies. Please contact R. Neri in case of doubts.

Data reduction

Proposers should be aware of constraints for data reduction:

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

Local contact

A local contact will be assigned to every proposal which does not involve an in-house collaborator. Depending upon the programme complexity, IRAM may require an in-house collaborator instead of the normal local contact.

Technical pre-screening

All proposals will be reviewed for both scientific interest and technical feasibility. Please, help us in this latter task by submitting technically precise proposals. Note that your proposal must be complete and exact: velocities, position and frequency setup must be exactly specified.

Non-standard observations

Please contact R.Neri, R.Lucas, or S.Guilloteau in case of doubt about non-standard program feasibility.

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

More specialized documents are also available; they are intended for observers on the site (IRAM on-duty astronomers, operators, or observers with non-standard programs):

Finally, we would like to stress again the importance of the quality of the observing proposal. The technical preparation of observing proposals is unfortunately often insufficient. In the past, proposals were received which did not even include exact observing frequencies or even source coordinates, or worse, with coordinates with the wrong epoch !... The IRAM interferometer is a powerful, but complex and unique instrument, and proposal preparation requires special care. Information is available in the documentation and at The IRAM staff can help in case of doubts if contacted well before the deadline. Note that the proposal should not only justify the scientific interest, but also demonstrate how the Plateau de Bure interferometer will bring new information.

Roberto NERI

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Next: Call for proposals on Up: IRAM Newsletter 38 (January Previous: Electronic proposal submission