Four primary 7 antenna configurations (see Table) are available that can be combined to produce maps with different
angular resolution. All four configurations are usually scheduled during the course of a year. During the summer period (May until
September) each antenna undergoes a thorough maintenance and the interferometer is operated in a 6 antenna D configuration, equal to the
7D configuration given in Table
but without station E10).
The four configurations can be used in different combinations to achieve complementary sampling of the uv-plane,
and to improve on angular resolution and sensitivity. The combinations AB, BC, CD are reasonably suited for all
declinations above 0(see Tables
to
). For lower source declinations, the beam becomes increasingly
elliptical. Sources lower than -25
declination cannot reasonably be observed from Plateau de Bure. Mosaicing is usually done with D
or CD, but the combination BCD can also be requested for high resolution mosaics.
The antenna half-power beam size is 50
at 100 GHz and the shortest possible antenna spacing is 24 m to avoid collisions between
two antennas. Even taking into account projection effects that shorten the effective baseline, sources larger than about 15
are
already heavily resolved at 100 GHz. In these cases, additional short-spacing observations should be acquired by observing a raster- or
OTF- (On-The-Fly) map using the IRAM 30 m telescope1. The short-spacing information can then easily be added to the uv-tables obtained from the interferometer by means of
the GILDAS MAPPING software.
Tables-
give a summary of possible beam sizes at various observing frequencies in different
configurations using natural weighting. The numbers were obtained assuming observations of the target source from 6 hours before to
6 hours after transit down to elevations above 20 degrees. Typical uv-coverages and resulting beam shapes for the seven-element array are
shown in Figs.
(D and CD),
(BCD and BC), and
(A and AB).
Dec. | 100 GHz | 150 GHz | 230 GHz | 300 GHz | 345 GHz | PA | |||||
Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | ![]() |
|
80 | 4.54 | 3.78 | 3.03 | 2.52 | 1.97 | 1.64 | 1.51 | 1.26 | 1.31 | 1.09 | 23 |
60 | 4.35 | 3.61 | 2.90 | 2.41 | 1.89 | 1.57 | 1.45 | 1.20 | 1.28 | 1.10 | 38 |
40 | 4.51 | 3.58 | 3.00 | 2.38 | 1.95 | 1.60 | 1.50 | 1.19 | 1.30 | 1.06 | 36 |
20 | 5.07 | 3.63 | 3.38 | 2.42 | 2.20 | 1.57 | 1.69 | 1.21 | 1.47 | 1.05 | 26 |
0 | 6.42 | 3.69 | 4.28 | 2.46 | 2.79 | 1.60 | 2.14 | 1.23 | 1.86 | 1.07 | -162 |
-20 | 9.80 | 3.36 | 6.53 | 2.24 | 4.47 | 1.47 | 3.26 | 1.12 | 2.98 | 0.98 | -173 |
Dec. | 100 GHz | 150 GHz | 230 GHz | 300 GHz | 345 GHz | PA | |||||
Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | ![]() |
|
80 | 3.44 | 2.72 | 2.29 | 1.81 | 1.49 | 1.18 | 1.14 | 0.90 | 0.99 | 0.78 | 23 |
60 | 3.29 | 2.59 | 2.19 | 1.72 | 1.43 | 1.12 | 1.09 | 0.86 | 0.95 | 0.75 | 34 |
40 | 3.45 | 2.55 | 2.30 | 1.70 | 1.49 | 1.10 | 1.15 | 0.85 | 0.99 | 0.73 | 32 |
20 | 3.96 | 2.56 | 2.64 | 1.70 | 1.72 | 1.11 | 1.32 | 0.85 | 1.14 | 0.74 | 25 |
0 | 5.09 | 2.60 | 3.39 | 1.73 | 2.21 | 1.13 | 1.69 | 0.86 | 1.47 | 0.75 | -161 |
-20 | 7.52 | 2.40 | 5.01 | 1.60 | 3.27 | 1.04 | 2.50 | 0.80 | 2.18 | 0.69 | -172 |
Dec. | 100 GHz | 150 GHz | 230 GHz | 300 GHz | 345 GHz | PA | |||||
Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | ![]() |
|
80 | 2.61 | 2.04 | 1.74 | 1.36 | 1.13 | 0.89 | 0.87 | 0.68 | 0.75 | 0.59 | 25 |
60 | 2.59 | 1.96 | 1.72 | 1.30 | 1.12 | 0.85 | 0.86 | 0.65 | 0.75 | 0.56 | 32 |
40 | 2.72 | 1.93 | 1.81 | 1.28 | 1.18 | 0.83 | 0.90 | 0.64 | 0.78 | 0.55 | 32 |
20 | 3.15 | 1.95 | 2.10 | 1.30 | 1.37 | 0.85 | 1.05 | 0.65 | 0.91 | 0.56 | 25 |
0 | 4.07 | 1.98 | 2.69 | 1.35 | 1.75 | 0.88 | 1.34 | 0.67 | 1.18 | 0.57 | 19 |
-20 | 6.13 | 1.88 | 4.09 | 1.25 | 2.66 | 0.81 | 2.04 | 0.62 | 1.77 | 0.54 | 8 |
Dec. | 100 GHz | 150 GHz | 230 GHz | 300 GHz | 345 GHz | PA | |||||
Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | ![]() |
|
80 | 1.91 | 1.56 | 1.27 | 1.04 | 0.83 | 0.67 | 0.63 | 0.52 | 0.55 | 0.45 | 35 |
60 | 1.91 | 1.48 | 1.27 | 0.98 | 0.83 | 0.64 | 0.63 | 0.49 | 0.55 | 0.43 | 45 |
40 | 2.08 | 1.48 | 1.39 | 0.99 | 0.90 | 0.64 | 0.69 | 0.49 | 0.60 | 0.43 | 40 |
20 | 2.60 | 1.56 | 1.73 | 1.04 | 1.13 | 0.68 | 0.86 | 0.52 | 0.75 | 0.45 | 26 |
0 | 3.72 | 1.64 | 2.48 | 1.09 | 1.61 | 0.71 | 1.24 | 0.54 | 1.07 | 0.47 | -162 |
-20 | 5.02 | 1.56 | 3.35 | 1.04 | 2.18 | 0.68 | 1.67 | 0.52 | 1.45 | 0.45 | 8 |
Dec. | 100 GHz | 150 GHz | 230 GHz | 300 GHz | 345 GHz | PA | |||||
Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | ![]() |
|
80 | 1.20 | 0.98 | 0.80 | 0.65 | 0.52 | 0.42 | 0.40 | 0.32 | 0.34 | 0.28 | 35 |
60 | 1.15 | 0.90 | 0.77 | 0.60 | 0.50 | 0.39 | 0.38 | 0.30 | 0.33 | 0.26 | 48 |
40 | 1.19 | 0.88 | 0.79 | 0.58 | 0.51 | 0.38 | 0.39 | 0.29 | 0.34 | 0.25 | 46 |
20 | 1.32 | 0.90 | 0.88 | 0.60 | 0.57 | 0.39 | 0.44 | 0.30 | 0.38 | 0.26 | 35 |
0 | 1.65 | 0.95 | 1.10 | 0.63 | 0.72 | 0.41 | 0.55 | 0.31 | 0.48 | 0.27 | 23 |
-20 | 2.44 | 0.92 | 1.63 | 0.61 | 1.06 | 0.40 | 0.81 | 0.30 | 0.71 | 0.26 | 10 |
Dec. | 100 GHz | 150 GHz | 230 GHz | 300 GHz | 345 GHz | PA | |||||
Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | Maj. | Min. | ![]() |
|
80 | 0.99 | 0.75 | 0.66 | 0.50 | 0.43 | 0.32 | 0.33 | 0.25 | 0.28 | 0.21 | 26 |
60 | 0.97 | 0.71 | 0.65 | 0.47 | 0.42 | 0.31 | 0.32 | 0.23 | 0.28 | 0.20 | 35 |
40 | 1.04 | 0.70 | 0.69 | 0.46 | 0.45 | 0.30 | 0.34 | 0.23 | 0.30 | 0.20 | 33 |
20 | 1.19 | 0.70 | 0.79 | 0.47 | 0.51 | 0.30 | 0.39 | 0.23 | 0.34 | 0.20 | 27 |
0 | 1.55 | 0.72 | 1.03 | 0.48 | 0.67 | 0.31 | 0.51 | 0.24 | 0.44 | 0.21 | 20 |
-20 | 2.31 | 0.68 | 1.54 | 0.45 | 1.00 | 0.29 | 0.77 | 0.22 | 0.66 | 0.19 | 10 |
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