Glossary for ALMA Data Processing

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  • Amplitude
  • Beam:
    • Primary beam
    • Synthesized beam (beam)
  • Calibrated data
  • Calibration
  • Calibration table
  • Clean
  • Continuum
  • Data Package
  • Doppler tracking
  • Executions
  • Image, Image cube
  • Imaging
  • Mask, clean mask
  • Measurement set
  • Quality Assurance
  • Phase
  • Scan
  • Scheduling block
  • Spectral frame
  • Spectral window
  • u,v distance: distance of a point in the Fourier plane (coordinate Ux, Vx) to the phase center in the Fourier plane (coordinates 0,0). The (u,v) distance of a visibility corresponds to the projected length of the corresponding baseline. It is s expressed either in meters or wavelength number (usually k[math]\displaystyle{ \lambda }[/math]). Generally speaking, visibilities with a short (u,v) distance contain information on large angular scales on the sky.
  • 'u,v plane', Fourier plane'

  • Visibility: the cross-correlation product of signals from two antennas. The data collected from the correlator in an interferometer consists of visibilities. They are complex numbers, whose argument is the phase and modulus is the amplitude. Visibilities coordinates are expressed in the Fourier Plane.