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Based on our winter 2002/2003 experience in carrying out configuration
changes with limited access to the Observatory, we plan again to
schedule three configuration changes next winter. We therefore ask
investigators to submit proposals for all four of the primary
configurations of the six antenna array. A preliminary configuration
schedule for the winter period is outlined below. Please note that the
more compact configurations (C and D) will be available only at the
end of January at the earliest. The scheduling priority will later be
adapted according to pressure in right ascension ranges and may
further be changed during the winter period depending on weather
conditions. The configuration schedule should be taken as
a guideline, in particular when astronomical targets are requested
that cannot be observed during the entire winter period (45sun avoidance circle).
||Scheduling Priority Winter 2003/2004
||November - December
||December - January
||February - March
||March - April
When the atmospheric conditions are not good enough at
1.3mm, 3mm projects will be observed: in a typical winter, 20-30% of
the time is found to be poor at 1.3mm, but still excellent at 3mm. We
therefore invite proposers to submit a significant number of proposals
also for observations at 3mm.
Under normal operating conditions, IRAM schedules and completes
between 40 to 60 projects during the winter period, with on average an
elapsed time of at least two months between start and end of a
project. Selection is based on scientific merit, technical
feasibility, and suitability for the instrument.
Details of the PdBI and the observing procedures are given in the
document ``An Introduction to the IRAM Plateau de
Bure Interferometer''. A
copy can be obtained from the address below or from the World-Wide-Web
at ./IRAMFR/PDB/docu.html). Proposers should
read this document carefully before submitting any proposal.
For this call for proposals, please note the following details.
Proposals should be submitted for one of the five categories:
The proposal category will have to be specified on the proposal cover
sheet and should be carefully considered by proposers.
- dual freq.:
- Proposals that ask simultaneously for
observations at 3mm and 1.3mm.
- Proposals that ask for 1.3mm data only. 3mm
receivers will be used for pointing and calibration purposes, but the
scientific goals of the proposal rely on the 1.3mm receivers.
- 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.
- 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 periods when only a subset of the standard
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 the tuning cannot be guaranteed,
and more generally all non-standard observations. These proposals will
be carried out on a ``best effort'' basis only.
The six antennas can be arranged in four primary configurations. The
current configurations for the winter period are:
Note that the stations of the current AB configuration set will
change, should station N46 on the northern track extension become
available in time for the winter 2003/2004 scheduling period.
- D alone is best suited for deep integration and coarse
mapping experiments. This configuration provides both the highest
sensitivity and the lowest atmospheric phase noise. It is slightly
more extended than the 5-element D configuration: the beam is smaller,
but slightly more elliptical.
- C provides a fairly complete coverage of the uv-plane
(low sidelobe level) and is well adapted to combine it with D for low
angular resolution studies (3.5'' at 100GHz, 1.5'' at
230GHz) and with B for higher resolution (2'' at 100GHz,
0.9'' at 230GHz). C alone is also well suited for snapshot
and size measurement experiments.
- B in combination with A already provides slightly higher
angular resolution (1.5'' at 100GHz). Short baselines have
been included to facilitate calibration (less decorrelation) and give
some sensitivity to extended structure, although this is clearly not
the primary goal of the AB configuration. It is mainly used for
relatively strong sources.
- A alone is well suited for mapping or size measurements
of very compact objects. It provides a resolution of 1.1'' at
100GHz, 0.5'' at 230GHz. In addition, because it contains
long, intermediate and some short baselines, it could still be used in
a tapered mode when a project is observed in marginal weather
conditions despite some loss of sensitivity (for backup projects).
The four array configurations can be used in different
combinations to improve on angular resolution and sensitivity.
Mosaicing is usually done with D or CD, but the combination BCD can
also be requested for high resolution mosaics. Enter ANY in
the proposal form if the scientific goals can be reached with any of
the four configurations or their subsets.
Please consult the documentation on the Plateau de Bure configurations
for further details.
All antennas are equipped with fully operational dual frequency
receivers. The available frequency range will be 82 to 116 GHz for
the 3mm band, and 205 to 245 GHz for the 1.3 mm band. The 3mm and
1.3mm receivers are aligned to within about 2''.
Below 105 GHz, receivers offer best performances in LSB tuning with
high rejection (20 dB): expected system temperatures are 100 to 150 K
for the winter time. Above 110 GHz, best performances are obtained
with USB tuning, low rejection (4 to 6 dB): expected system
temperatures are 250 K at 115 GHz.
The 1.3 mm receivers have DSB tuning with typical T
50 K. Expected SSB system temperature are 250 to 350 K. The
guaranteed tuning range is 205-245 GHz, but it may be possible to
reach some lower and higher frequencies. Higher frequencies are not
feasible on all antennas because of limitations in the triplers,
however. For details about observing at frequencies adjacent to the
guaranteed tuning range of the 3mm and 1.3mm receivers, please consult
The rms noise can be computed from
Investigators have to specify the one sigma noise level which is
necessary to achieve each individual goal of a proposal, and
particularly for projects aiming at deep integrations.
is the system temperature (150 K below 110 GHz, 200 K at
115 GHz, 400 K at 230 GHz for sources at
is the conversion factor from Kelvin to Jansky (22 Jy/K at
3mm, 35 Jy/K at 1.3mm)
is an efficiency factor due to atmospheric phase noise
(0.9 at 3 mm, 0.8 at 1.3 mm)
is the number of antennas (6), and
is the basic number
of configurations (1 for D, 2 for CD, 2 for BC, and so on)
is the on-source integration time per configuration
in seconds (2 to 8 hours, depending on source declination). Because of
calibrations and antenna slew time, the effective on-source time is
about 70% of the total observing time.
- B is the spectral bandwidth in Hz (580 MHz for continuum, 40
kHz to 2.5 MHz for spectral line, according to the spectral correlator
The interferometer operates in the J2000.0 system. For best
position 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 new correlator has 8 independent units which can independently be
placed anywhere in the 110-680 MHz band. Seven modes of configuration
are available, characterized in the following by couples of total
bandwidth/number of channels. In the 3 DSB modes (320MHz/128,
160MHz/256, 80MHz/512 - see Table) the two central channels may be
perturbed by the Gibbs phenomenon if the continuum is strong. 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 SSB modes (160MHz/128, 80MHz/256,
40MHz/512, 20MHz/512) the two central channels are not affected by the
Gibbs phenomenon and, therefore, these modes are preferable for
Note that 5% of the passband are left out at the
low-frequency and at the high frequency ends of each subband. The 8
units can be independently placed either on the 3mm or 1.3mm
For safety reasons, the sun avoidance circle has been extended to 45
degrees. Please take this into account for your sources and the
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.
Proposers should be aware of constraints for data reduction:
Data reduction will be carried out on dedicated computers at
IRAM. Remote data reduction is possible, and especially for
experienced user of the Plateau de Bure Interferometer. Please contact
R.Neri if you are interested in reducing the data from your home
- In general, data should be reduced in Grenoble. Proposers will
not come for the observations, but may 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.
- In certain cases, proposers may have a look at the uv-tables as
the observations progress. If necessary, and upon request, more
information can be provided. Please contact us if you are interested
- CLIC is still evolving to cope with upgrades of the PdBI
array. The newer versions are downward compatible with the previous
releases, but the reverse is not true. Observers who wish to finish
data reduction at their home institute should obtain the most recent
version of CLIC. Because differences between CLIC versions may
potentially result in imaging errors if new data are reduced with an
old package, we insist that observers having a copy of CLIC take
special care in maintaining it up-to-date.
A local contact will be assigned to every A or B rated proposal which
does not involve an in-house collaborator. He will assist you in the
preparation of the observing procedures and provide help to reduce the
data. Assistance is also provided before a deadline to help newcomers
in the preparation of a proposal. Depending upon the programme
complexity, IRAM may require an in-house collaborator instead of the
normal local contact.
All proposals will be reviewed for technical feasibility in addition
to the scientific review by the programme committee. Please help in
this task by submitting technically precise proposals. Note that your
proposal must be complete and exact: the source position and velocity
as well as the requested frequency setup must be correctly given.
If you plan to execute a non-standard program, please contact R.Neri
or R.Lucas to discuss the feasibility.
The documentation for the IRAM Plateau de Bure Interferometer includes
documents of general interest to potential users, and more specialized
documents intended for observers on the site (IRAM on-duty
astronomers, operators, or observers with non-standard programs). All
documents can be retrieved on our Web page at ./IRAMFR/PDB/docu.html
Finally, we would like to stress again the
importance of the quality of the observing proposal. The IRAM
interferometer is a powerful, but complex instrument, and proposal
preparation requires special care. Information is available in the
documentation at .IRAMFR/PDB/docu.html. The IRAM staff
is prepared to provide help if contacted well before the deadline. Note
that the proposal should not only justify the scientific interest, but
also the need for the Plateau de Bure Interferometer.
Next: VLBI Observations and Call
Up: IRAM Newsletter 56 (August 2003)
Previous: News from the Plateau