The Calibration Pipeline reduces skydips measurements in quasi-real
time, in an automatic way. The skydips can be used to chack the
water content and forward efficiency parameters of the astronomy
receivers, but also of the WVR receivers; the derived parameters
should be consistently determined.
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).
- A skydip measurement has been performed, consisting in several
atmopheric calibration scans, observed at different
elevations.
- Input: for each atmospheric calibration scan
- For each observation: auto-correlations for all spectral channels
and all antennas, averaged over the observation integration time.
- WVR data.
- 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.
- Antenna elevation.
Basic Course:
- Check data consistency.
Exception course: If data not consistent: stop processing and return
a specific error code.
- Process each calibration scan: see Use Case
ProcessAtmosphericCalibration.
- Compute the antenna's forward efficiencies and atmospheric
opacities (possibly as a function of frequency) .
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:
- For each antenna: forward efficiencies (possibly: as a function
of frequency), 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 skydips measurements requires the
spectral visibilities and the WVR data. The two data sets
should be used to derive astmospheric parameters in a consistent
way.
Owner: Frederic Gueth