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Galactic nuclei showing recurrent phases of activity and quiescence haverecently been discovered, with recurrence times as short as a few hours to aday -- known as quasi-periodic X-ray eruption (QPE) sources -- to as long ashundreds to a thousand days for repeating nuclear transients (RNTs). Here wepresent a multi-wavelength overview of Swift J023017.0+283603 (hereafter SwiftJ0230+28), a source that exhibits repeating and quasi-periodic X-ray flaresfrom the nucleus of a previously unremarkable galaxy at $\sim$ 165 Mpc, with arecurrence time of approximately 22 days, an intermediary timescale betweenknown RNTs and QPE sources. The source also shows transient radio emission,likely associated with the X-ray emission. Such recurrent soft X-ray eruptions,with no accompanying UV/optical emission, are strikingly similar to QPEsources. However, in addition to having a recurrence time that is $\sim 25$times longer than the longest-known QPE source, Swift J0230+28's eruptionsexhibit somewhat distinct shapes and temperature evolution than the known QPEsources. Scenarios involving extreme mass ratio inspirals are favored over diskinstability models. The source reveals an unexplored timescale for repeatingextragalactic transients and highlights the need for a wide-field, time-domainX-ray mission to explore the parameter space of recurring X-ray transients.

X-ray eruptions every 22 days from the nucleus of a nearby galaxy