Delta Use Case for EVLA Observing - Polarization, v2

Bryan Butler


As described in the main use case document, subsequent use cases from 
that one will be presented as "delta" use cases - only providing 
steps that are different from those in the main use case.  This is the 
first of these delta use cases, describing continuum observing at an 
intermediate frequency (X- or C-band), but for an observation that is 
concerned with polarization.

  I. Proposal Preparation and Submission
        4. necessary resources, including configuration, frontend(s),
           backend (correlator) setup.  Here, a specification must be
           made on which polarization products will be recorded.
        5. source information: position, flux density, size, 
           polarization properties
        7. time needed
           a) in order to figure out how much time is needed, the user 
              may do one of:
              (3) for polarization observations, the observer must 
                  input a required circular or linear polarization 
                  accuracy in both fractional amplitude and in the 
                  accuracy of the angle of linear polarization, if 
                  linear polarization is required (sensible defaults 
                  should be provided).  This may drive the required 
                  observing time, along with necessary calibrations and 
           b) for polarization observations, there may be constraints 
              on the time needed based on parallactic angle coverage.

 II. Observation Preparation
     C. the user then specifies the following:
        2. a source list, containing all of the sources of interest
           g) a sequence of observations - including the cycle time 
              between source and phase calibrator, and when to observe 
              the flux density and, if needed, polarization angle and 
              instrumental polarization calibrators.  Note that 
              sensible defaults should be provided, of course.
           i) for polarization observations, associated polarization 
              angle calibrators (might be the same for many sources)
           j) for polarization observations, associated instrumental 
              polarization calibrators (may be the same as the phase
              calibrators specified above, but for polarization 
              observations, the requirements are slightly different).

III. During Observing

     nothing beyond the default use case...

 IV. After Observing (Data Access)

     nothing beyond the default use case...