... The MIDAS Data Organizer, a customizable utility to analyze and identify associations in a database of astronomical observations, is described. ... On-line Data Reduction: . ... The main characteristics of the on-line implementation of the DO at the ESO New Technology Telescope (NTT) are described below. The database for all operations is a MIDAS (ESO-IPG 1993) table, the so-called Observation Summary Table (OST) which contains all relevant parameters extracted from the FITS keywords. ...