Microwave flux density variations of compact radio sources monitored by real-time very long baseline interferometry

Compact and strong radio sources were repeatedly observed in regular geodet ic very long: baseline interferometry experiments under the Key Stone Proje ct. The flux densities of these sources in the S and X bands were estimated front a set of correlated amplitudes obtained through the correlation proc essing of the observed data. From similar to5 years of the observed data, i rregular variations in the flux densities were detected fur several radio s ources using the source 2134 + 004 as the calibrator. The results showed th e monitoring of flux density variations by means of very long baseline inte rferometry is feasible. Since the correlation processing of the observed da ta are performed real-time using a high-speed digital communication techniq ue, this method gives a capability to monitor Aux density variations of qua sars and BL-Lac types of extragalactic radio sources.