Use Case: ProcessCalibratorAmplitude


The calibration pipeline compute from the complex visibilities measured on a calibrator antenna-based amplitudes for this calibrator. The intrinsic calibrator flux being known (e.g. measured at sesssion start), the gain of each antenna (expressed in K/Jy) is estimated. This allows us to detect antenna problems (e.g. poor pointing and/or poor focus) and receiver problems (e.g. electronic LO phase jitter at the observing frequency).

Those computation must be done in an automatic way and in quasi-real time.

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

Priority: ***

Performance: < second

Frequency: seconds

Preconditions:

  1. The processing of calibrator amplitude is initiated by the Calibration Pipeline after each scan on an amplitude calibrator.
  2. Input:
    • Baseline based pseudo-continuum complex visibilities;
    • A priori flux of calibrator;
    • Reference values of antenna gains.

Basic Course:

  1. Compute antenna-based amplitudes from complex visibilities.

    2. Exception Course: Stop processing and return a specific error code.
  2. Compute antenna gains.

    3. Exception Course: Stop processing and return a specific error code.
  3. Check for problems (how???) and accordingly set an alarm flag.

    4. Exception Course: Stop processing and return a specific error code.


Postconditions:

  1. Output:
    • Estimated antenna gains (absolute and/or ratio to reference values);
    • Alarm flag;
    • Error code.
  2. The output is fed back to the Calibration Pipeline.


Issues to be Determined or Resolved:

  1. Should separation between phase and amplitude be recomputed both here and in ProcessCalibratorPhase? If not, input parameter should be changed.

Notes:

  1. ***

Owner: Jerome Pety.
Last modified by $Author: lucas $ on $Date: 2003/02/14 12:13:08 $