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tokens: of relatively pristine gas inflows in the local Universe, given the metallicity cut-off seen for LGRB progenitors. Our discovery of strong H ii region emission located at the explosion site of AT 2018cow appears a strong means to link the progenitor with ongoing star formation, and thus young (massive) stellar populations. This in contrast to inference from observing cold inflows of neutral gas, which provide an even more indirect indicator of current star formation. We note, however, that it is very difficult to make conclusive statements on a single object, given almost any location in a galaxy will have a significant line-of-sight population of old stars. 5.2 Tidal-disruption event Other explanations for AT 2018cow have been proposed that may not involve a massive star at all. One such scenario is the tidal disruption of a main-sequence star or white dwarf by an IMBH (Kuin et al. 2019 ; Perley et al. 2019 ). In the main-sequence TDE scenario (Perley et al. 2019 ), a BH mass of ∼10 4.3 M ⊙ is required. Such an IMBH would be expected to be located within a massive stellar cluster. For the case of a young parent cluster, we do indeed find a star-forming region underlying AT 2018cow, however, the explosion site is significantly offset from the peak of this source in both the white-light image of our MUSE cube and the centroid of the H α emission, where one would expect the massive IMBH to settle towards rapidly. For an older, globular cluster (GC) host, the hosting GC would lie at the upper end of the GC luminosity function (Harris 1996 ). A magnitude of the host of M V , ∼ − 9 to −11 mag follows from both extending the M–σ relation (e.g. Gültekin et al. 2009 ) to IMBH masses, and looking at the luminosities of GCs with signs of IMBHs (e.g. Noyola et al. 2010 ; Feldmeier et al. 2013 ; Lützgendorf et al. 2013 ). At the distance of CGCG 137-068 this would appear as a m V ∼ 23−25 mag source at the explosion site, and should be detectable in high-resolution imaging of the site. An alternate scenario, involving a more massive BH ∼10 5–6 M ⊙ and a low-mass white dwarf was presented by Kuin et al. ( 2019 ). Although white dwarfs may form at a few × 10 7 yr after star formation (Portegies Zwart, McMillan Makino 2007 ), i.e. comparable to the age we infer for the underlying H ii at the explosion site of AT 2018cow), these are the most massive white-dwarfs – low-mass white-dwarfs will form much later. In this case the co-location with star formation is a coincidence in this scenario. This BH required mass is comparable to that of a massive GC itself, and a dwarf satellite galaxy of CGCG 137-068 may be a more promising BH-host system. Notwithstanding the lack of spatial coincidence we find between AT 2018cow and the peak of any underlying source, we searched in our data for existence of a distinct system in the vicinity. In Fig. 6 , we show the results of fitting individual spaxels in a region surrounding the explosion site of AT 2018cow to look for