We present the results of a two-year long optical monitoring program of the narrow-line Seyfert 1 galaxy Akn 564. The majority of this monitoring project was also covered by X-ray observations (RXTE) and for a period of ∼ 50 days, we observed the galaxy in UV (HST) and X-rays (RXTE & ASCA) simultaneously with the groundbased observations. Rapid and large-amplitude variations seen in the X-ray band, on a daily and hourly time-scale, were not detected at optical and UV wavelengths, which in turn exhibited much lower variability either on short (one day) or long (several months) time-scales. The only significant optical variations can be described as two 2-4 day events with ∼ 10% flux variations. We detect no significant optical line variations and thus cannot infer a reverberation size for the broad-line region. Similarly, the large X-ray variations seem to vanish when the light curve is smoothed over a period of 30 days. The UV continuum follows the X-rays with a lag of ∼ 0.4 days, and the optical band lags the UV band by ∼ 2 days. No significant correlation was found between the entire X-ray dataset and the optical band. Focusing on a 20-day interval around the strongest optical event we detect a significant X-ray-optical correlation with similar events seen in the UV and X-rays. Our data are consistent with reprocessing models on the grounds of the energy emitted in this single event. However, several large X-ray flares produced no corresponding optical emission.

ABSTRACT. New UBVRI photometry has been obtained for the W UMa eclipsing system AM Leonis. The data have been used to derive nine times of minimum and to construct light curves. The minimum timings show that the system recently had a significant period increase. Modeling of the light curves shows AM Leo to be an overcontact system with a mass ratio of 2.51. Both Rucinski & Duerbeck's absolute magnitude calibration for W UMa stars applied to our photometry and the radial velocity curve combined with our derived parameters indicate a distance near 125 pc, larger than the 77 pc from the Hipparcos parallax.

Abstract.Results of a ground-based optical monitoring campaign on NGC 5548 in June 1998 are presented. The broad-band fluxes (U , B, V ), and the spectrophotometric optical continuum flux F λ (5100Å) monotonically decreased in flux while the broad-band R and I fluxes and the integrated emission-line fluxes of Hα and Hβ remained constant to within 5%. On June 22, a short continuum flare was detected in the broad band fluxes. It had an amplitude of about ∼18% and it lasted only ≈90 min. The broad band fluxes and the optical continuum F λ (5100Å) appear to vary simultaneously with the EUV variations. No reliable delay was detected for the broad optical emission lines in response to the EUVE variations. Narrow Hβ emission features predicted as a signature of an accretion disk were not detected during this campaign. However, there is marginal evidence for a faint feature at λ 4962Å with F W HM 6Å redshifted by ∆v 1100 km s −1 with respect to Hβnarrow.

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