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We identify a previously undetected periodicity at a frequency of49.08$\pm$0.01 d$^{-1}$ (period of 29.34$\pm$0.01 minutes) during asuper-outburst of V844 Her observed by TESS. V844 Her is an SU UMa typecataclysmic variable with an orbital period of 78.69 minutes, near the periodminimum. The frequency of this new signal is constant in contrast to thesuperhump oscillations commonly seen in SU UMa outbursts. We searched withoutsuccess for oscillations during quiescence using MDM, TESS, and XMM-Newtondata. The lack of a periodic signal in the XMM light curve and the relativelylow X-ray luminosity of V844 Her suggests that it is not a typical IP. Weconsider the possibility that the 29 min signal is the result of super-Nyquistsampling of a Dwarf Nova Oscillation with a period near the 2-minute cadence ofthe TESS data. Our analysis of archival AAVSO photometry from a 2006super-outburst supports the existence of a 29 min oscillation, although apublished study of an earlier superoutburst did not detect the signal. Wecompare the X-ray properties of V844 Her with short orbital period intermediatepolars (IP), V1025 Cen and DW Cnc. We conclude that the new signal is a realphotometric oscillation coming from the V844 Her system and that it is unlikelyto be an aliased high-frequency oscillation. The steady frequency of the newsignal suggests that its origin is related to an asynchronously rotating whitedwarf in V844 Her, although the precise mechanism producing the flux variationsremains unclear.

A Surprising Periodicity Detected During a Super-outburst of V844 Herculis by TESS