Use Case: ProcessSidebandRatio
The Calibration Pipeline reduces sideband ratio measurements in
quasi-real time, in an automatic way. The control system needs the
results for further observations.
Role(s)/Actor(s):
Primary: Calibration Pipeline
Secondary:
Priority: Major
Performance: Seconds
Frequency: Hours
Preconditions:
-
The processing is initiated by the Calibration Pipeline (see Use Case
ProcessCalibrations).
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One or several observations of a strong point-like source have been obtained,
belonging to one or several contiguous scans.
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Input:
-
Visibilities for all spectral channels, averaged over the total integration
time.
-
Parameters for frequency smoothing (method and associated parameters).
Basic Course:
-
Check data consistency.
Exception course: If data not consistent: stop processing and
return a specific error code.
-
Optionaly: smooth/average the data along the frequency axis.
Exception course: If failure: stop processing and return a specific
error code.
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Compute the side band ratio (as a function of frequency) for each antenna.
Exception course: If failure: stop processing and return a specific
error code.
-
Verify that result is sensible and set quality code.
Exception course: If failure: stop processing and return a specific
error code.
Alternate Course:
Postconditions:
-
Outputs:
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For each antenna: side band ratio as a function of frequency, associated
uncertainties, and quality code.
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Error code.
Issues to be Determined or Resolved:
-
To obtain a frequency-dependant side band ratio, bandpass
calibration should a-priori not be applied, as the bandpass
measurement itself depends on the side band ratio.
Notes:
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The processing of the side band ratio measurements requires the spectral
visibilities, corrected for atmospheric absorption.
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The processing of the side band ratio measurements and that of the atmopsheric
calibration are thus coupled.
-
The processing of the side band ratio measurements requires at least three
antennas be available in the array.
Owner: Frederic Gueth