VSX J003909.7+611233: a new Slowly Pulsating B star (SPB) in Cassiopeia?

We report the discovery of a new 13th magnitude variable in Cassiopeia close to the variable KP Cas. Analysis of 6 days of intensive photometry shows a regular, near sinusoidal modulation with an amplitude of 0.024 magnitudes and a period of 0.43815(31) d. Although its colour indicates a spectral type around F0 the star probably suffers up to 2 - 2.5 magnitudes of extinction so could be an A- or B-type star. Given the period, the low amplitude, the shape of the light curve and the probable spectral type we consider it most likely to be a slowly pulsating B-type (SPB) star. The variable has been registered in the International Variable Star Index with the identifier VSX J003909.7+611233.