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We present the 2005-2010 outburst history of the SUUMa-type dwarf HS0417+7445,along with a detailed analysis of extensive time-series photometryobtained in March 2008 during the second recorded superoutburst of the system.The mean outburst interval is 197 \pm 59 d, with a median of 193 d. The March2008 superoutburst was preceeded by a precursor outburst, had an amplitude of4.2 magnitudes, and the whole event lasted about 16 days. No superhumps weredetected during the decline from the precursor outburst, and our data suggestsinstead that orbital humps were present during that phase. Early superhumpsdetected during the rise to the superoutburst maximum exhibited an unusuallylarge fractional period excess of epsilon = 0.137 (Psh = 0.0856(88) d).Following the maximum, a linear decline in brightness followed, lasting atleast 6 days. During this decline, a stable superhump period of Psh =0.07824(2) d was measured. Superimposed on the superhumps were orbital humps,which allowed us to accurately measure the orbital period of HS 0417+7445, Porb= 0.07531(8) d, which was previously only poorly estimated. The fractionalsuperhump period excess during the main phase of the outburst was epsilon =0.037, which is typical for SU UMa dwarf novae with similar orbital period. Ourobservations are consistent with the predictions of the thermal-tidalinstability model for the onset of superoutbursts,but a larger number ofsuperoutbursts with extensive time-series photometry during the early phases ofthe outburst would be needed to reach a definite conclusion on the cause ofsuperoutbursts.

The orbital and superhump periods of the dwarf nova HS 0417+7445 in Camelopardalis