ProcessAtmosphericCalibration

Use Case: ProcessAtmosphericCalibration

The Calibration Pipeline reduces atmospheric calibration measurements in quasi-real time, in an automatic way. The system
is halted until the results are available.

Role(s)/Actor(s):
Primary: Calibration Pipeline
Secondary:

Priority: Major

Performance: Seconds

Frequency: Minutes

Preconditions:

The processing is initiated by the Calibration Pipeline (see Use Case ProcessCalibrations).
An atmospheric calibration scan has been obtained, consisting in one or several observations of the sky and a hot load.
Input:

For each observation: auto-correlations for all spectral channels and all antennas, averaged over the observation integration time.
Side band ratios for each antennas.
Weather station data: external temperature, humidity, pressure.
Parameters for frequency smoothing (method and associated parameters).
Calibration mode to be used.

Basic Course:

Check data consistency.

Exception course:

Optionaly: smooth/average the data along the frequency axis.
Exception course: If failure: stop processing and return a specific error code.
Depending on the calibration mode, compute what has to be computed.

Exception course:

Verify that result is sensible and set quality code.

Exception course:

Alternate Course:

Postconditions:

Outputs:

For each antenna: system temperature, receiver temperature, atmospheric water vapor, opacities, ... with the associated uncertainties and quality code.
Error code

Results are fed back to the Calibration Pipeline.

Issues to be Determined or Resolved:

The Science IPT is still thinking about the atmospheric calibration scheme. Depending on the final decision, all sections of this Use Case may be affected.

Notes:

The processing of the atmospheric calibration measurements requires the spectral visibilities.

The processing of the atmosheric calibration and that of the side band ratio measurements are coupled.

Owner: Frederic Gueth