12.3 Data editing

Editing the interferometer data is not very flexible when done in the uv tables. If a problem occurs, is is not easily diagnosed since many of the parameters associated with the data acquisition are not present: atmospheric data, total powers, ... It is however useful when something strange occurs in the mapping process to do uv plots of the input table to look for the faulty data. Using time or scan number as X coordinate is recommended. One then may go back to the CLIC program and flag the faulty data, tag the corresponding scans, and keep a log of these problems so that they are not encountered again when the uv tables are reconstructed for any reason.

Two tasks have been written that may directly edit the data in uv tables:

UV_CLIP flags all visibilities larger than a given flux: this deletes visibility points with totally wrong numbers, if any.

UV_FLAG deletes visibility points in a give time interval for a given baseline.

Both tasks work by setting the corresponding weight to zero: their action is irreversible (you will have to reconstruct the uv table to go back).

The MAPPING program provides a more efficient, simpler and reversible interactive tool to flag parts of a uv data set (command UV_FLAG).