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

We report the discovery of a new 13th magnitude variable star in Cassiopeia close to the variable KP Cas.Analysis of six days of intensive photometry shows a regular, near sinusoidal modulation with an amplitude of 0.024 mag 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 Aor B-type star. Given the period, the low amplitude, the shape of the lightcurve 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

The first confirmed superoutburst of the dwarf nova GALEX J215818.5+241924

In 2011 October an optical transient was reported in Pegasus as a possible nova. The object had an ultraviolet counterpart, GALEX J215818.5+241924. In this paper we present follow-up photometry of the object which revealed the presence of superhumps, with peak-to-peak amplitude of up to 0.22 magnitudes, diagnostic of it being a member of the SU UMa family of dwarf novae. The outburst amplitude was 4.6 magnitudes and it lasted at least 10 days, with a maximum brightness of magnitude 14.3. We determined the mean superhump period from our first 5 nights of observations as Psh = 0.06728(21) d. However analysis of the O-C residuals showed a dramatic evolution in Psh during the outburst. During the first part of the plateau phase the period increased with dPsh/dt = +2.67(15) x 10-4. There was then an abrupt change following which the period decreased with dPsh/dt = -2.08(9)x 10-4. We found a signal in the power spectrum of the photometry which we tentatively interpret as the orbital signal with Porb = 0.06606(35) d. Thus the superhump period excess was epsilon = 0.020(8), such value being consistent with other SU UMa systems of similar orbital period.Comment: Accepted for publication in the Journal of the British Astronomical Association. 10 pages, 3 figures. arXiv admin note: text overlap with arXiv:1005.5378. Have corrected outburst amplitude, reworded the first 2 sentences of the Abstract for clarity and solved some typo