CLEAN_NKEEP

    This  is an integer specifying the minimum number of Clean components before
    testing if Cleaning has converged. The convergence is criterium is a compar-
    ison of the cumulative flux evolution separated by  CLEAN_NKEEP  components.
    If th

    IF  CLEAN_NKEEP is 0, CLEAN will ignore this convergence criterium, and con-
    tinue clean until the CLEAN_NITER, CLEAN_ARES or CLEAN_FRES  criteria  indi-
    cate to stop.

    With  CLEAN_NKEEP  >  0, CLEAN will explore the stability of the total clean
    flux over the last CLEAN_NKEEP  iterations. For a positive (resp.  negative)
    source, if the Clean flux becomes smaller (resp. larger) than the Clean flux
    CLEAN_NKEEP iterations earlier, CLEAN will stop.

    Using CLEAN_NKEEP about 70 is a reasonable value.  Some special cases (faint
    extended sources) may require larger values of CLEAN_NKEEP.