Preparing old and recent radio source tables for the VO age: Current
  status
  Independent of established data centers, and partly for my own research, I
have been collecting the tabular data from nearly 1500 articles concerned with
radio sources. Optical character recognition (OCR) was used to recover tables
from nearly 600 of these. Tables from only 44 percent of these articles are
available in the CDS or CATS catalog collections. This fraction is 62 percent
for articles with over 100 sources. Surprisingly, these fractions are not
better for articles published electronically since 2001, perhaps partly due to
the fact that often tabular data are published in formats not useful for direct
machine reading. The databases Simbad and NED recognize only about 60 percent
of the bibliographic references corresponding to the existing electronic radio
source lists, and the number of objects associated with these references is
much smaller still. Both, object databases like NED and Simbad, as well as
catalog browsers (VizieR, CATS) need to be consulted to obtain the most
complete information on radio sources. More human resources at the data centers
and better collaboration between authors, referees, editors, publishers, and
data centers are required to improve the flow of tabular data from journals to
public databases. Current efforts within the Virtual Observatory (VO) project,
to provide retrieval and analysis tools for different types of published and
archival data stored at various sites, should be balanced by an equal effort to
recover and include large amounts of published data not currently available in
this way. If human resources can be found, the data sets collected by the
author will be made available for the preparation of metadata necessary for
their ingression into catalog browsers.
