ALMA Strawperson Zoom - B Array Equivalent

Physical Descriptions:

  1. Maximum baseline 2327 m
  2. Minimum baseline 32 m
  3. Maximum near-in sidelobe 2%

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) :



(left panel) Pad distribution superimposed onto terrain and uv coverage. (Middle panel) Pads (open circles) and antennas (filled circles) superimposed on the 5deg gradient mask. (Right panel) UV coverage and distribution of pad density versus radius. Yellow line indicates best fitting gaussian.

Beams, Snapshot and 4hr synthesis :


(Left panel) Zenith snapshot dirty beam. The plotted grayscale ranges between -5% and +10%. The peaks sidelobe between radii of 1 and 22 beams is 0.0456. (Right panel) Long track dirty beam for a dec=-23 sources observed +/-2hrs from transit. Note all antennas weights assumed equal and image is naturally weighted. The peak sidelobe within 20 beams is 0.0215.

Comparsion beams for the twin ring strawperson design:


(Left Panel) The plotted grayscale ranges between -5% and +10%. (Right panel) Long track dirty beam for a dec=-23 sources observed +/-2hrs from transit. Note all antennas weights assumed equal and image is naturally weighted. The peak sidelobe within 20 beams is 0.0385.

Comparsion uv density distributions for snapshots (click for higher resolution):


Comparison between the zoom and double ring uv coverages. Blue refers to the zoom design and red to the double ring design. About 4% of the spiral uv points lie beyond the outer edge of the double ring uv coverage.