SDSSp J173008.38+624754.7 : New long-period SU UMa-type dwarf nova

T. Kinnunen reported an outburst of this object from 14.7 to 13.9mag on October 18 (vsnet-campaign 1192). On October 22, T. Vanmunster and A. Oksanen independently reported the detection of superhumps which revealed this object to be an SU UMa-type dwarf nova. The light curve showed a typical superhump profile whose amplitude was about 0.40mag and relatively long period in SU UMa stars (vsnet-campaign 1195, vsnet-campaign 1196). The Kyoto team also confirmed the superhumps (vsnet-campaign 1195), and T. Kato reported there was some evidence of superimposed QPOs with a period of ~10 min (vsnet-campaign-dn 1769). The VSNET collaboration team has received the data from the Kyoto team, T. Vanmunster, and the Nyrola team. The combined data shows a periodicity of 0.079294(34) d and possible period shortening (vsnet-campaign-dn 1790). The object gradually faded with a rate of 0.13mag/d in the plateau phase of the superoutburst (vsnet-campaign-dn 1790). The rapid fading from the outburst was reported on October 29 (vsnet-campaign-dn 1801). T. Vanmunster performed time-series observations on October 28/29 and reported the revised superhump period to be 0.07933(4)d (vsnet-campaign-dn 1803). His data showed rapid decline with a rate of 3mag/d. M. Uemura reported the humps were still visible in the light curve on October 28 and 29. In October 28 light curve, we can see the sudden growth of a late superhump. On October 29, the phase of humps was apparently shifted (vsnet-campaign-dn 1810). The gradual fading continued at least until October 30 when the Kyoto team detected a possible humps in the light curve (vsnet-campaign-dn 1819). The light curve on October 31 shows sinusoidal variations, which indicates the object almosr returned to quiescence (vsnet-campaign-dn 1831). The observation on November 6 by the Kyoto team showed the object brightened again. This brightening may be a post-superoutburst rebrightening, or may represent the start of the phase of recurring normal outbursts. In the latter case, the recurrence time is expected to be short as inferred by the observation (vsnet-campaign-dn 1849).

The Kyoto team detected a minor brightening of an amplitude of 1.4mag on December 11 (vsnet-campaign-dn 1973).

Other related articles: vsnet-campaign 1742, 1750, 1755, 1758, 1759, 1760, 1763, 1768, 1770, 1772, 1774, 1777, 1778, 1779, 1781, 1783, 1786, 1787, 1792, 1795, 1804, 1806,

CCD image presented by A. Oksanen:
Light curve by T. Vanmunster: