SDSS J162718.39+120435.0--a dwarf nova a in the period gap

SDSS J162718.39+120435.0 was suspected of being a dwarf nova from spectroscopic observations made available by the Sloan Digital Sky Survey. Photometry conducted during the 2008 outburst, the first ever outburst of this object detected and followed up in real time, shows that the outburst reached magnitude 14.6 at maximum, had an amplitude of 4.7 magnitudes and lasted for at least 18 days. Common superhumps were detected with an amplitude of up to 0.4 magnitudes, confirming it to be a member of the SU UMa family. Initially the superhump period, [P.sub.sh], was 0.10993(7) days (2.638 hours), but it subsequently reduced to [P.sub.sh] = 0.10890(9) days (2.614 hours) later in the outburst. The period change corresponds to the end of the plateau period of the outburst. The orbital period, [P.sub.orb], was estimated from the two [P.sub.sh] values as between 0.1026 and 0.1016d, which places SDSS1627 near the centre of the period gap in the orbital period distribution of cataclysmic variables.