ALMA Strawperson Donut/Double-Ring B Array

Physical Descriptions:

  1. Maximum baseline 1430 m
  2. Minimum baseline 36 m
  3. Maximum near-in sidelobes are about 5%.
  4. The outer sidelobes are strongly suppressed by earth rotation synthesis (less than 2.4%).

Pad Positions:

The X and Y positions are with respect to a reference position on the 5 degree mask. To convert to SAM56 coordintes:

SAM56 E = 624820 + X

SAM56 N = 7449700 + Y

Array Layout, UV Distribution, Synthesized Beam (snapshot):



(Upper left panel) Pad distribution shown with the "5 degree slope" mask in red. The blue square marks the current position of the NRAO test equipment container. (Upper right panel) Snapshot UV distribution and pad postions from CONFI. (Lower left panel) Snapshot dirty beam. The plotted color ranges between -5% (blue) and +10% (red). Maximum near-in sidelobe 5.6% and the largest sidelobe inside the PB is about 14%. (Lower right panel) Radial density distribution of the visibility points for a snapshot observation. Only 1.3% of the UV cells are sampled.

UV Distribution, Synthesized Beam (4 hr synthesis):


(Left panel) A dirty beam after a 4 hour long earth rotation synthesis. The plotted color ranges between -5% (blue) and +10% (red). While the near-in sidelobes remain more or less the same (4.8%) as the snapshot case (above), the outer sidelobes are strongly suppressed by earth rotation synthesis (less than 2.4%). (Right panel) Radial density distribution of the visibility points. About 40% of the UV cells are sampled after 4 hours of observations.