by @cas02 and represents continuum flux of UV. All the UV 1455Å  model light curves also follow the same timescaling law as that of free-free emission light curves. In other words, if we properly squeeze the timescales of novae, these theoretical light curves converge into one [see Figure 18 of @hac06kb]. The main part of theoretical free-free emission light curve decays as $F_\nu \propto t^{-1.75}$. @hac06kb called this property the universal decline law of classical novae.

Because the decline rate of optical light curve is a good indicator of the WD mass, we can estimate the WD mass from comparison of the theoretical light curve with the observed optical one. If multiwavelength light curves are available, we are able to determine the WD mass more accurately. Using multiwavelength light curves in optical, UV 1455Å, and supersoft X-ray turn-on/turnoff times, @hac06kb [@hac10k; @hac16k] determined the WD masses of V1974 Cyg and V1668 Cyg. The UV 1455Å  band flux represents the photospheric emission in the wind phase while the supersoft X-ray flux does in the post-wind phase. These multiwavelength data are so useful because their dependences on the WD mass and chemical composition are different. It should be noted that the soft 