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We report simultaneous X-ray and optical observations of V404 Cyg inquiescence. The X-ray flux varied dramatically by a factor of >20 during a 60ksobservation. X-ray variations were well correlated with those in Halpha,although the latter include an approximately constant component as well.Correlations can also be seen with the optical continuum, although these areless clear. We see no large lag between X-ray and optical line variations; thisimplies they are causally connected on short timescales. As in previousobservations, Halpha flares exhibit a double-peaked profile suggesting emissiondistributed across the accretion disk. The peak separation is consistent withmaterial extending outwards to at least the circularization radius. The promptresponse in the entire Halpha line confirms that the variability is powered byX-ray (and/or EUV) irradiation.Comment: 5 pages; Accepted for publication in the Astrophysical Journal  Letter

Correlated X-Ray and Optical Variability in V404 Cygni in Quiescence