Long-term variability of 3C 273 at 22 and 44 GHz

Observations of 3C 273 at 22 and 44 GHz during the past 7 yr are presented. Between 1981 and 1984, the QSO was in a high-flux-density state at both frequencies, the intensity decreasing by a factor of 2 during 1985, reaching a minimum value in April 1986. The changes in the flux density were larger at 44 GHz and preceded the changes at 22 GHz. The variability in 1983 was identified with the millimeter and infrared outburst of February 1983, and the observed flux-density fluctuations were correlated with the appearance of the superluminal knots observed at 10.7 GHz with VLBI techniques. 46 references.