I found a memory leakage issue in pyfits.new_table, data were NOT deleted when the table was deleted, I prepared a test on github, using objgraph , which shows that data are still in memory:
https://gist.github.com/884298
the issue was solved by Erik Bray of STSCI on March 28th, 2011 , see bug report:
http://trac6.assembla.com/pyfits/ticket/49
and changeset:
http://trac6.assembla.com/pyfits/changeset/844