Use Case:  Associate data complementary in terms of u,v coverage.

For projects requiring a dynamic range in spatial frequencies the observations will be done in pieces several month apart depending on the array reconfiguration scheme. These data must gathered in an ObservationUnit with associations at different level in the Project Structure.

Goal: Invoking the archive, generate an ObservationUnit with a recursive structure in the intent to produce images with DataMembers having complementary u,v coverages.

Contact Author:   F.Viallefond

Role(s)/Actor(s):
Primary:   ASA user (astronomer)
Secondary:   RSC staff (operators, astronomers)

Priority: Very desirable

Frequency:  Few times a week?

Preconditions: 

  1. Database is running
  2. User got authenticated
  3. The project identification(s) is (are) known.

Basic Course: 
  1. Connect to the ASA via ACS from the home institute
    Alternate Course: none
    Exception Course: Connection can't be established: try again until timeout.
    Postcondition: Connection established.
  2. Amongst the available services listed when the connection is established, select the service which allows to create an ObservationUnit; this opens a GUI for an interactive high level interface which maps user request into XPath queries.
    Alternate Course: select an interface to submit a script for batch mode request
  3. In case of interactive mode, from the GUI, the user provides the project identification(s). There may be a single project identifier if the intent was to use several antenna configurations when the project started, else it could be two or a few identifiers. In this later case the list of identifiers could be generated automatically (relevant information being provided in the SCHEDULE intent and or EXECUTE intent).
    If the user provides a list of identifiers the system checks that indeed these are compatible to increase the u,v coverage.
    Exception Course: No complementary data available. The basic course is terminated
    If there are observations scheduled for complementarity but not yet observed, the user is informed.
    Alternate Course: The data are not strictly compatible (e.g. small shift in the reference velocity, slightly different correlator setup etc...). In these cases the association could be accepted but with a warning adressed to the user, some extra processing being subsequently necessary.
  4. The ObservationUnit is generated forming e.g. as many DataCollection as there are project identifiers or as many DataMembers in a single DataCollection when there is a single project identification (the internal logic for various possible structures will need to be defined).
  5. The subsequent basic courses are identical to those of the AssociateMultiFreq Use Case, when the user is left with 3 possibilities.

Postconditions:

  1. An ObservationUnit in an adequate format available (for an elapsed time TBD) for reprocessing at the RSC in case alternate processing methods would be desired.
  2. Image with the combined u,v coverage; it is a member of type image in a new higher level DataCollection, the alternative being that it is a higher level ObservationUnit if the association concerns more than one project identifier.

Issues to be Determined or Resolved:  

The concepts of ObservationUnits and DataCollections or any altenative project structure need to be agreed and designed first. The details for the structuration of associations would benefit also of standard definitions in at least a number of standard cases such as those invoked in this Use Case.

Last modified: Sun Oct 12 23:02:50 CEST 2003