Use Case:  Check Antenna Gain Solution.

The calibration pipeline checks antenna gains by receiving archived results (summary tables and eventualy plots) and hardware characteristics to be used as references. It eventually adds in the data-base of monitered parameters the new results.

Goal: Retrieve from archive hardware properties and update with new measurements.

Contact Author:   F.Viallefond

• Calibration Pipeline.
  
• Control: performance monitoring.
  

• Operator, Staff Astronomer, Interactive Observer.
  

Priority: Critical

Performance:   < second

Frequency:  seconds.

Preconditions: 

1. Database is running
2. A priori flux of calibrator known (FindSrcUseCase Basic course for Amplitude/phase and/or Primary flux calibrators excuted
3. Antenna-based amplitudes from complex visibilities determined (ProcessCalibratorAmplitude Basic cource 1).
4. Antenna gains computed for the list of antenna identifiers with their feeds used and the sky frequency (ProcessCalibratorAmplitude Basic course 2).

1. Retrieve from archive the antenna gains previously determined from observations obtained in approximatively same conditions (feed, frequency, elevation).
   Alternate Course: No antenna gains known for those conditions.
   
   1. skip the 2 next items in the basic course.
      
2. Scale these gains for the sky frequency of the gains to be checked.
   
3. Determine the means and rms of these archived antenna-gains for each antenna, restricting to those obtained since the most recent hardware setup.
   
4. Determine the distances of the current antenna-gains to those means in rms units.
   
5. Extract from the archive the characteristics of the antennas (surface efficiencies, aperture blockage, feed spillover efficiency).
   
6. Publish these results for ProcessCalibratorAmplitude Basic course 3.
   
7. Archive the results if ProcessCalibratorAmplitude did not set an alarm flag.
   

Postconditions:

1. Archive updated with new antenna-gains values

Issues to be Determined or Resolved:   None

Notes:   This Use Case was created by F. Viallefond.