Open Access

Table 1

Summary of the data simulation parameters using CASA.

Parameter Value Notes
Antenna configuration ALMA Cycle 5.3
Number of antennas 50
Field COSMOS J2000 10h00m28.6s + 02d12m21.0s
Number of pointings or simulations 9164 Every pointing is randomly chosen within a radius of 1 deg around the field.

Central frequency Band 6 (230 GHz)
Number of channels 240
Channel width 7.8 MHz
Sampling time 10s
Total integration time 20 min
Hour angle Transit

Sky model dimensions 512 × 512 pixel with 240 channels
Pixel size 0.1″
Source type Gaussian The size of the major/minor axis and position angle is varied randomly and is chosen to be below the synthesized beam.
Major (minor) axis 0.4″ to 0.8″ Typical resolution is 0.89″ × 0.82″.
Position angle (PA) 0–360 deg Chosen randomly.
Number of sources 0–5 Randomly chosen between 1 and 5. We add a few source free simulations.
Source positions Random Sources are randomly distributed within the primary beam.
Flux range 0.05–0.5 mJy The flux of each source is randomly chosen from this range assuming a uniform distribution. This roughly keeps a flat S/N range for our data set.
Spectral index 0 We set this parameter to zero since the fractional bandwidth is quite small (0.8%).

Primary beam 22.86″
Synthesized beam 0.89″ × 0.82″
Noise (PWV) 1.796 This parameter adds the receiver and atmospheric noise due to water vapor to the visibilities.
Weighting Natural
Robust 0.5
RMS noise (in images) ~50 µJy

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