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We report results from a search for small-amplitude intra-night optical variability microvariability in 11 radio quiet, but optically bright and luminous, quasi-stellar objects. The observations were made using CCD's as N-star photometers on telescopes in Chile and India. The reduced data reveal indications of microvariability for several of the sources, but in no case has the reality of the fluctuations been clearly established.
Observations of this type can discriminate among various theoretical mechanisms proposed for the origin of optical microvariability in AGNs. In particular, clear detections of microvariability in radio quiet QSOs would favor models where flares or other instabilities on accretion disks are responsible for the small fluctuations. On the other hand, statistically convincing evidence that such fluctuations are absent in radio quiet objects would support models based on shocks propagating down the relativistic jets which are only associated with radio loud AGN. Preliminary data for several sources have been published (Gopal-Krishna, Sagar \& Wiita, 1993, MNRAS, 262, 963) and final results on the newer observations will be submitted soon (Gopal-Krishna et al. 1994).
This work was supported in part by NSF grant AST9102106.
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