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Observing proposals are invited for the IRAM Plateau de Bure
Interferometer (PdBI), for Nov. 15, 1994 to May 15, 1995 . The deadline for applications
is Monday, September 12th 1994 . The available frequency range will be 82 GHz to 116
GHz. We hope to be able to offer in addition two specific
opportunities for a fraction of the time
- very long baselines (E24
- 230 GHz band for a test and demonstration period
below for details.
Details of PdBI and operations are given in the document
``An Introduction to the IRAM Plateau de Bure
Interferometer'' (copies can
be obtained from the address below, or from Internet via the
World-Wide-Web and NCSA-Mosaic software; use IRAM home page
http://iram.fr/iram.html). Proposers should read this document
carefully before submitting any proposal.
Proposals should be sent to
IRAM Scientific Secretariat
Interferometer Observing Proposal
Rue de la Piscine
F-38406 Saint Martin d'Hères Cedex
IRAM expects to schedule and complete between 20 to 30 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.
For this call for proposals, please note the following opportunities:
- Very long baselines
We are have started the extension of the baselines of the
interferometer, adding stations W20, W23, W27 and N29. We anticipate
that only the West track extension (W20, W23 and W27) will be
completed before the winter.
Proposals which could benefit from these long East-West baselines can
be submitted with an explicit mention ``Long East-West baselines
request''. Only a very limited number of such proposals will be
considered. Because the whole extension will not be complete, the
exact configuration(s) offered is (are) not yet defined. Observers are
welcome to make propositions, in particular about the number of extra
configurations required (one or 2 ?), but the final choice will remain
- 230GHz receivers
IRAM plans to equip 2 antennas with dual-frequency receivers by the
end of September. The 4 antennas might be equipped with such receivers
by January 1995. The new dual-frequency systems have the following
- SSB tuning between 82 and 115 GHz. This brings a factor 2 improvement
in sensitivity at 115 GHz when compared to the current system.
- DSB tuning between 210 and 240 GHz. Expected is about 80 K.
- Simultaneous observing at both frequencies. Each of the 6 units of the
correlator can be connected to one or the other receiver.
Performances at 230 GHz will require some extensive testing. In order
to benefit most from these added capabilities, and to perform the best
tests, IRAM is calling for ``Tests or Demonstration projects for
the 230 GHz system''. The following restrictive conditions will apply
for these projects:
- All projects should be suited for a test period: there is no implied
guarantee of completion as for normal proposals.
- Test projects should be feasible with 2 or 3 antennas.
- Pointing accuracy is not expected to be better than 3.
- Test projects should clearly explain what aspect of the interferometer
they will test, and what scientific result is expected in case of
- Proposals should mention `` Test project for the 230 GHz
system'' or `` Demonstration project for the 230 GHz system''.
- Demonstration projects will be carried out only if all 4 antennas are
equipped, and only if the previous tests were successful.
- IRAM may require either an in-house collaborator, or the presence
of one of the investigators on the site during the test period, or
quick data reduction of the project by the investigators in Grenoble,
or any combination of the above requests depending on project
- All projects should have an associated 3mm project to be carried out
simultaneously. The associated project will not benefit from the
normal ``guarantee of completion'', unless specifically requested in
the proposal. Only one proposal should be submitted for both projects.
- The tests will obviously start with short baselines (D configuration).
Long baselines (B2 configuration) will be tested also, but use of the
``very long'' baselines is unlikely.
Other relevant information:
- 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
- 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
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. Combination of all configurations (BCD, 5 configurations
in total), is possible, but must be justified even more carefully.
- 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
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.
- 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 in the middle of the
band of the correlator unit.
- All receivers can be tuned in lower side band 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 side band tuning
(e.g. to observe one spectral line in each band), please specify it.
This LSB tuning will also be possible between 113 GHz and 115.3 GHz.
- 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.
- 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 will be carried out on the dedicated HP
- 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.
- New versions of CLIC are
upward compatible with previous ones, but the reverse is not true. Observers
wanting to finish data reduction at their home institute should obtain
an up-to-date version of CLIC. 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.
- Local contact:
- Depending upon the program complexity, IRAM may
suggest an in-house collaborator instead of the normal local contact.
- Technical screening:
All proposals will be reviewed for technical feasibility in parallel
to being sent to the members of the program committee. Please help in
this task by submitting technically precise proposals. Scientific
justification should be kept within 2 pages. Note that your proposal
must be complete and exact: velocities, position and frequency setup
must be exactly specified.
- Non-standard observations:
- Please contact 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 to
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 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.
Next: Call for ``Letters
Up: IRAM Newsletter
Thu Mar 9 14:24:13 MET 1995