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Using a month-long X-ray lightcurve from ${\it RXTE}$/PCA and 1.5 month longUV continuum lightcurves from ${\it IUE}$ spectra in 1220$-$1970 $\r{A}$, weperformed a detailed time-lag study of the Seyfert 1 galaxy NGC 7469. Ourcross-correlation analysis confirms previous results showing that the X-raysare delayed relative to the UV continuum at 1315 $\r{A}$ by 3.49 $\pm$ 0.22days which is possibly caused by either propagating fluctuation or variablecomptonisation. However, if variations slower than 5 days are removed from theX-ray lightcurve, the UV variations then lag behind the X-rays variations by0.37$\pm$0.14 day, consistent with reprocessing of the X-rays by a surroundingaccretion disc. A very similar reverberation delay is observed between ${\itSwift}$/XRT X-ray and ${\it Swift}$/UVOT UVW2, U lightcurves. Continuumlightcurves extracted from the ${\it Swift}$/GRISM spectra show delays withrespect to X-rays consistent with reverberation. Separating the UV continuumvariations faster and slower than 5 days, the slow variations at 1825 $\r{A}$lag those at 1315 $\r{A}$ by $0.29\pm0.06$ day, while the fast variations arecoincident ($0.04\pm0.12$ day). The UV/optical continuum reverberation lag from${\it IUE}$, ${\it Swift}$ and other optical telescopes at differentwavelengths are consistent with the relationship: $\tau \propto \lambda^{4/3}$,predicted for the standard accretion disc theory while the best-fit X-ray delayfrom ${\it RXTE}$ and ${\it Swift}$/XRT shows a negative X-ray offset of$\sim$0.38 days from the standard disc delay prediction.

Evidence for variability timescale dependent UV/X-ray delay in Seyfert 1 AGN NGC 7469