This database is the ISO (Infrared Space Observatory) Observation Log of Validated Data. ISO is an ESA (European Space Agency) project with instruments funded by ESA member states (especially the PI countries of France, Germany, the Netherlands and the United Kingdom), and with the participation of ISAS (Japan) and NASA (USA). ISO operated from November 1995 till May 1998, almost a year longer than expected. As an unprecedented observatory for infrared astronomy, able to examine the cool and hidden places in the Universe, ISO successfully made nearly 30,000 scientific observations. The ISO data can be retrieved from the ISO Data Archive (<a href="http://iso.esac.esa.int/ida/">http://iso.esac.esa.int/ida/</a>;), which is available at the ISO Data Centre (<a href="http://iso.esac.esa.int/">http://iso.esac.esa.int/</a>;), and comprises about 150,000 observations, including calibration, parallel mode and serendipitous observations. The present catalog contains all observations performed in standard observing modes exempt from technical problems; special flags indicate calibration observations. The catalog gives observation details and provides links to quick-look images depicting the data and to observation-specific documentation. The ISO helpdesk can be reached at <a href="http://iso.esac.esa.int/esupport/">http://iso.esac.esa.int/esupport/</a>; This online catalog was last updated by the HEASARC in September 2004 based on the machine-readable table <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VI/111/isolog.dat.gz">https://cdsarc.cds.unistra.fr/ftp/cats/VI/111/isolog.dat.gz</a>; obtained from the CDS data center. This is a service provided by NASA HEASARC .