ALMA Strawperson Zoom - BnC Array Equivalent
Physical Descriptions:
- In moving from a C-array to a B-array configuration
(a total of 32 antenna moves) we can move the first 18
telescopes to preferentially occupy the Northern and Southern pads to
give an array suitable to observe Northern hemisphere of far
South sources.
- Note we can move directly from C to BnC in a burst
reconfiguration of the 18 antennas over one or two days
or more gradually, moving 1-2 antennas per day. After finishing
in BnC array we can then reconfigure the antennas for B array
(12 antenna moves).
Antenna Positions:
Antenna positions are given here in meters
in UVCON format . The X and Y positions
are with respect to a reference position on the 5 degree mask.
To convert to SAM56 coordintes:
SAM56 E = 628340 + X
SAM56 N = 7453250 + Y
Array Layout, UV Distribution (click for higher resolution) :
Antenna distribution superimposed onto terrain and the snapshot
uv coverage for a transiting Dec +30 source.
Details of main lobe (click for higher resolution):
(Left Panel) Contour representation of the snaphsot main beam observing
a dec=+30 source at transit. The fitted beam FWHM is 178 x 153 mas. At the
50% contour the ratio of NS to EW dimension is 1.15.
(Right panel) Long track dirty beam for a dec=+30 sources observed
+/-2hrs from transit. The fitted FWHM is 176 x 160mas. Note all
antennas weights are assumed equal and image is naturally weighted.
At the 50% contour the axial ratio is 1.10.
Beams, Snapshot and 4hr synthesis :
(Left panel) Snapshot dirty beam for Dec +30 source ovserved at transit.
The plotted grayscale ranges between -5% and +10%. The
fitted beam FWHM is 178x153 mas.
(Right panel) Long track dirty beam for a dec=+30 sources observed
+/-2hrs from transit. Note all antennas weights assumed equal and
image is naturally weighted. The fitted beam FWHM is 176 x 160 mas.