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tokens: at +1542d (Stritzinger et al. 2012 ), and SN 2010jl at +461 day and +573 day (Fransson et al. 2014 ). Other coronal lines detected in SN 2017ens are similar to those seen in SN 2010jl (Figure 3 , bottom panel): [Fe x ] λ 6374.5 is strong, as are [Fe xi ] λ 7891.8, [Ne v ] λλ 3345.8, 3425.9, [Ca v ] λ 6086.8, and [Ar x ] λ 5533.2. The presence of these lines is indicative of a highly ionized and dense CSM, although we do not detect the highest-ionization coronal lines such as [Fe xiv ] λ 5302.9 and [Ar xiv ] λ 4412.3, which were seen in SN 2005ip. The flux ratio of the [O iii ] λ 4363 to λ 5007 lines is a function of the CSM density and temperature. Following Fransson et al. ( 2014 , their Figure 26), we use our measured flux ratio, log( λ 4363/ λ 5007) = −0.22, to constrain the CSM electron density to lie between 10 6 and 10 8 cm −3 for T e = 50,000 to 10,000 K. This density range is consistent with that observed for SN 2010jl. From our mid-resolution X-Shooter data, we resolve narrow P-Cygni profiles on top of the ∼2000 km s −1 wide Balmer and Paschen lines. We measure the blueshifted wavelength from the absorption component of the H γ , H β , and H α P-Cygni profiles, which suggests that the unshocked CSM has a low velocity of ∼50 km s −1 . A similar velocity of ∼60 km s −1 is obtained from the P-Cygni profile of the He i λ 10,830 line. Moreover, we measure the FWHM intensity of the wide components, such as H α (2500 ± 700 km s −1 ), H β (2300 ± 400 km s −1 ), Pa γ (2000 ± 200 km s −1 ), and He i λ 10,830 (2200 ± 200 km s −1 ). We also detect narrow absorption lines from the Balmer series (no clear emission), spanning H to H33 (3659 Å). In addition, we see emission from the H ii region close to the host-galaxy center (see Figure 4 , marked B1), as part of a faint galaxy (SDSS J120409.47–015552.4) with g = 21.92 ± 0.24 mag ( M g ≈ −16.5 mag). These lines have a slightly different redshift ( z = 0.1084) than SN 2017ens. In particular, the (noisy) detection of the weak auroral [O iii ] λ 4363 line indicates a low host-galaxy metallicity of ∼0.04–0.4 Z ⊙ using the direct T e -based method. If we instead use the empirical N2 metallicity diagnostic (Pettini Pagel 2004 ), we measure Z = 0.3 ± 0.2 Z ⊙ 4. Bolometric Light Curve and Model Fitting Using all of our available UV-through-NIR photometry, we built a pseudobolometric light curve for SN 2017ens using the prescription from Inserra et al. ( 2018b ). The results are very similar to those derived when using a blackbody fit, as expected as our photometry covers a large wavelength range. From a polynomial fit to the bolometric data we obtain L bol = (5.86 ± 0.20) × 10 43 erg s −1 at peak and an integrated energy of (3.53 ± 1.42) × 10 50 erg. To fit our bolometric light curve, we used a two-component model consisting of a central heating and an interaction component. First, the centrally heated component uses the standard Arnett method (Arnett 1982 ; Inserra et al. 2013 ). We tested three possible