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We propose to obtain the first deep observations in the UV (currently constrained only with the XMM-Newton OM) with high cadence HST FUV imaging of aQPE with eruptions lasting only 27 min and recurring every 114 min. Thesetimescales are perfectly suited to perform the first time-resolved UVvariability search during the X-ray eruptions. With HST sensitivity in the FUVthis will lead to a >2 orders of magnitude improvement compared to currentconstraints. A detection of UV variability and how it correlates with the X-rayswill have field-defining implications that will redraw the theoreticallandscape. Non-detections will provide very strong additional constraints on thegeometry extent and properties of the putative accretion disks [truncated! Please see actual data for full text]