Bridging the gap: OPTICAM reveals the hidden spin of the WZ Sge star GOTO 065054.49+593624.51

WZ Sge stars are highly evolved accreting white dwarf systems (AWDs) exhibiting remarkably large amplitude outbursts (alsoknown as superoutbursts), typically followed by short rebrightenings/echo outbursts. These systems have some of the lowestmass transfer rates among AWDs, making even low magnetic fields dynamically important. Such magnetic fields are often invoked to explain the phenomenology observed in these systems, such as their X-ray luminosity and long periods of quiescence (30+ yr). However, the detection of these is very elusive given the quenching of the accretion columns during outburst and thelow luminosity of these systems during quiescence. Here, we present high-cadence multiband observations with OPtical TImingCAMera of the recent outburst of the recently discovered WZ Sge star GOTO 065054.49+593624.51, during the end of the main outburst and the dip in-between rebrightenings, covering two orders of magnitude in brightness. Our observations revealthe presence of a statistically significant signal with P_ω ≃ 148 s in the bluer (g) band, which is detected only during the dip between the main outburst and the rebrightenings. We interpret this signal as the spin period of the AWD. If confirmed, GOTO065054.49+593624.51 would bridge the gap between intermediate- and fast-rotating intermediate polars below the period gap.