Arti Goyal1*,Gopal-Krishna2Ram Sagar,1 G. C.
Anupama3 6and D. K. Sahu3
1 Aryabhatta Research Institute of Observational Sciences (ARIES) Nainital 263 129
2 National Centre for Radio Astrphysics (NCRA), TIFR, Pune 411 007
3 Indian Institute of Astrophysics (IIA) Bangalore 560 034
Abstract. Although well established for BL Lac ob jects and radio-loud quasars, the occurrence of intra-night optical variability (INOV) in radio-quiet quasars is still debated, primarily since only a handful of INOV events with good statistical significance, albeit small amplitude, have been reported so far. This has motivated us to continue intra-night optical monitoring of bona-fide radio- quiet quasars (RQQs). Here we present the results for a sample of 11 RQQs monitored by us on 19 nights. On 5 of these nights a given RQQ was monitored simultaneously from two well separated observatories. In all, two clear cases and two probable cases of INOV events were detected. From these data, we estimate an INOV duty cycle of 8% for RQQs which would increase to 19% if the `probable variable' cases are also included. Such comparatively small INOV duty cycles for RQQs, together with the small INOV amplitudes (1%), are in accord with the previously deduced characteristics of this phenomenon.
Keywords: galaxies: active - galaxies: nuclei - galaxies: jets - quasars: general - BL Lacertae ob jects: general
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