Optical to UV spectral energy distribution of OV Boo. Shown are the pre-outburst spectra from the HST (Uthas et al. 2011) and the SDSS, and pre-outburst SDSS ugri photometric data, together with post-outburst photometric data from the OM and AAVSO (this work). All observed pre-outburst data are shown in black, the two post-outburst data points in blue. White dwarf model spectra for 14 and 23 kK, are shown in red and blue, respectively. Flux units are 10⁻¹⁵ erg cm⁻² s⁻¹ Å⁻¹. The 23 kK spectrum was shifted downwards by 0.239 units to account for the non-WD part of the spectrum, whose brightness is indicated by the short blue dashed line at 3000 Å.